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Walschaert Valve Gear 

BREAKDOWNS 

AND 

HOW TO ADJUST THEM 



BY 

CALVIN F. SWINGLE, M. E. 

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FULLY ILLUSTRATED 




PUBLISHERS 

FREDERICK J. DRAKE & CO 

CHICAGO, U. S. A. 

1908 



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[uSrARY of CONGRESS] 

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COPYRIGHT 1908 

BY 

FREDERICK J. DRAKE & CO. 

CHICAGO 




THE WALSCHAERT VALVE GEAR. 

INTRODUCTION. 

Egide Walschaert, the designer of the valve gear that 
bears his name, worked like Watt, Stephenson, and other 
great inventors to solve the problem for future genera- 
tions. He produced his invention in the year 1844 when 
the locomotive was yet in its infancy as compared with 
modern practice. He wrought much better than he 
knew, for his work now fulfills a need that did not 
really exist at the time, but his gear today appears to be 
almost indispensable to meet the conditions which have 
arisen in consequence of the development of the loco- 
motive. 

It is altogether fitting, therefore, that a short histor- 
ical sketch of the man, and his work, be inserted in this 
connection, as it will prove to be not only interesting, 
but helpful to the student. The author desires also to 
acknowledge his indebtedness to Mr. Carl J. Mellin, 
Consulting Engineer from the American Locomotive 
Company, for valuable information, diagrams, etc., per- 
taining to the Walschaert valve gear. The author is also 
under obligations to the Baldwin Locomotive Works, 
and the American Locomotive Company for descriptive 
details, cuts, etc., relative to the design, construction and 
operation of this valve gear. 



HISTORICAL. 

The following is a history of Walschaert and his valve 
motion by Prof. M. J. Boulvin of the University of 
Ghent, which was published in the Railroad Gazette of 
November 24, 1905, and is here reproduced by permission 
of that journal. 

Egide Walschaert died on the 18th of February, 1901, 
at Saint-Gilles, near Brussels, at the age of eighty-one 
years. His mechanism, which is so original, has been 
adopted for many years in most of the countries of Eu- 
rope and has been wrongly attributed to Heusinger 
von Waldegg. He was born January 21, 1820, at 
Malines, which place became, fifteen years later, the 
central point of the System of Belgian Railways. The 
line from Brussels to Malines was opened in 1835, and 
this event decided the career of young Walschaert. 
Three years later, at the exhibition of products of 
M alines, there appeared some remarkable models exe- 
cuted by him, and described as follows in the catalogue : 

No. 19. M. E. Walschaert, Jr., student of the Muni- 
cipal College. 

a. A stationary steam engine of iron (the main 
piston having the diameter of 4.5 c. m. or 1.77 in.). 

b. A working model of a locomotive in copper to the 
scale of 1/20 of the railway locomotives. 

c. Section of a stationary steam engine. 

d. Model of a suction pump and a duplex pump. 

e. Glass model of an inclined plane. 

Minister Rogier was so much struck by it that he had 
Walschaert enter the University of Liege, but his studies 

2 



HISTORICAL 6 

were interrupted by a serious illness, and were never 
completed. We find traces of him at the National Ex- 
hibition in Brussels in 1841. The report of the jury men- 
tions with praise a small locomotive constructed entirely 
by Walschaert, and a steamboat 6.50 meters long and 
I.75 meters wide, which was capable of carrying sixteen 
men and traveling (so the report says) at four leagues 
an hour on the canal. 

The boiler of this little boat was of a new system in- 
vented by the constructor. The jury does not give fur- 
ther details. Walschaert received the silver medal. 

In 1842 Walschaert was taken into the shops of the 
State Railway at Marines as a mechanic. Machine tools 
existed only in the most rudimentary forms, and the 
storerooms were badly provisioned. The lack of organ- 
ization in the shops rendered a man of Walschaert's 
abilities particularly valuable, and at the end of two 
years he was made shop foreman at Brussels. Although 
he was only twenty-four years of age he had already 
shown the qualities which make an engineer, which 
should have carried him in a few years to be the tech- 
nical head of the motive power department. It is humil- 
iating to be compelled to say that he remained shop fore- 
man throughout his life. 

The first locomotives came from England and had 
not been in service for more than ten years when Wal- 
schaert was made foreman. The railroad was growing 
rapidly and it was necessary to increase the forces and 
to acquire experience. Walschaert was not content 
with the duties incurred in these difficult circumstances, 
but began his career by the invention of his system of 
valve motion. 

On October 5, 1844, Mr. Fischer, Engineer of the 
Belgian State Railways, filed for Egide Walschaert an 



4 THE WALSCHAERT VALVE GEAR 

application for a patent relating to a new system of steam 
distribution applicable to stationary steam engines and 
to locomotives. The Belgian patent was issued on No- 
vember 30, 1844, for a term of fifteen years. The rules 
of the department did not allow a foreman to exploit a 
Belgian patent for his own profit and this explains prob- 
ably the intervention of Mr. Fischer, who has never 
claimed the slightest part, material or moral of the in- 
vention. 

On October 25th, of the same year, Walschaert took 
out a patent in France for the same invention. There 
also exists among the documents left by the inventor, a 
contract signed at Brussels in 1845 by Demeuldre, from 
which it appears that he undertook to obtain a patent of 
importation into Prussia for the new valve motion, sub- 
ject to an assignment by Walschaert of half of the 
profits to be deducted from the introduction of the new 
valve motion in this country. It is probable, however, 
that this contract was never carried out. 

The design attached to the Belgian patent is repro- 
duced in Figure 1. In this primitive arrange- 
ment the link oscillated on a fixed shaft, in re- 
gard to which it was symmetrical, but it had an enlarged 
opening at the center so that only at the ends was it 
operated without play by the link block, which was made 
in the form of a simple pin. There was one eccentric, 
the rod of which terminated in a short T carrying two 
pins. The reverse shaft operated the eccentric rod and 
maintained it at the desired height. For one direction 
the lower pin of the T engaged in the lower end of the 
link, and to reverse the engine the rod was raised so that 
the upper pin engaged in the upper end of the link. The 
angle of oscillation of the link varied with the position 
of the pin in the link, and this oscillation was trans- 



HISTORICAL 




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mitted by an arm to the combining lever, which was also 
operated by the cross-head. 

The central part of the link could not be used for 
the steam distribution, as it was necessary to enlarge it 
to allow for the plan of the pin which was not in oper- 
ation. It may be asked why the inventor used two sepa- 
rate pins mounted on a crosspiece on the end of the ec- 
centric rod instead of a single pin on the center of the 
rod which would have served for both forward and 
backward motion without requiring the center enlarge- 
ment of the link. It must be borne in mind that the rais- 
ing or lowering of the eccentric rod by the reverse shaft 
was equivalent to a slight change in the angular advance 
of the eccentric. Consequently with a link of a sufficient 
length to keep down the effect of the angularity it was 
necessary to reduce as much as possible the movement 
of the eccentric rod. Notwithstanding its differences 
the mechanism described in the patent of 1844 1S m prin- 
ciple similar to the valve motion with which every one 
is today familiar and which the inventor constructed as 
early as 1848, as is shown by a drawing taken from the 
records of the Brussels shops, on which appears the in- 
scription: "Variable Expansion; E. Walschaert's sys- 
tem applied to Locomotive No. 98, Brussels, September 
2, 1848/' 

Figure 2, taken from this drawing, shows the valve 
motion as we know it today. For although it is true 
that the link and the combining lever are usually placed 
in a different position so as to shorten the eccentric rod 
and the valve stem, yet the design of the locomotive 
often requires an arrangement similar to that shown 
in Fig. 2. The system which Hensinger von Wald- 
egg invented in 1849, an d which he applied in 1850 to 
1 85 1, differs only in a few insignificant particulars from 



HISTORICAL 




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8 THE WALSCHAERT VALVE GEAR 

that shown in Fig. I. Walschaert had therefore pre- 
ceded him. There are at the present time many systems 
of steam distribution, and the progress made in kine- 
matics has greatly facilitated their development. 

At the time, however, of Walschaert's work there was 
but one system of valve motion that was at all exten- 
sively used, viz., that of Sharp, with two eccentrics hav- 
ing forked rods. The link credited to Stephenson w r as in- 
vented by Howe in 1843, an d it is doubtful whether 
Walschaert had ever seen it. 

A problem which nowadays appears very simple was, 
for the investigators of that time, extremely complicated, 
and the man who discovered the most correct solution, 
which has yet been put forward, certainly merits hon- 
orable mention and unreserved admiration. Notwith- 
standing his arduous w T ork at the Brussels shops, where 
he built, with limited facilities, several new locomotives, 
Walschaert did not lose sight of the problem of steam 
navigation. 

The records show that he appeared at the National 
Exposition at Brussels in 1847 with a screw yacht that 
proved to be a success. The propeller had several blades, 
each one with only a small part of the thread similar to 
those of the modern screws. Walschaert had invented 
this arrangement himself, without knowing of the re- 
sults obtained by Normand w 7 ith the Corse in 1841 or 
1842. Locomotive practice had taught him the intimate 
correlation which should exist between the engine and 
the boiler and in this machine he made use of a boiler 
of high power which attracted much attention. A similar 
machine was built a little later by the Couillet Co., as is 
shown by the plan drawn up in 1853. This machine is 
compact and light. The documents which remain do not 
mention the pressure or the speed. It was non-con- 



HISTORICAL bf 

densing, and in all probability the exhaust steam assisted 
the draft. 

During the years which followed, Walschaert's activity 
was given entirely to his duties as foreman and it is dif- 
ficult to determine his part, which was valuable though 
anonymous, in the design of the railroad equipment. He 
is credited with the differential throttle in which the 
opening of an auxiliary slide on the back of the main 
slide assisted the opening of the valve. He also designed 
a brake with shoes acting on the rails which was used for 
a long time in switching locomotives and in which the 
principle of a lever acting near its dead point was applied 
in an ingenious manner. 

It was very remarkable that his initiative spirit did not 
suffer from his long services under an administration 
with so much complicated routine. It is possible that he 
found a stimulant in the adoption of a large number of 
his ideas by the Great Central Belgian Railway and in en- 
couragement which, without making him rich, kept his 
intelligence on the alert. He took an important part for 
many years in the design of the motive power of this rail- 
road, which was rendered the more difficult by reason of 
the difficult profile of the lines terminating in Charleroi 
and by the heavy traffic to be handled. The design of 
the freight locomotives for heavy grades, built in 1862 
for the Great Central, belongs entirely to Walschaert. 
The company built more than one hundred locomotives 
from the original plans without making any important 
alterations. These locomotives have not been without 
their influence on the Belgian shops in which they were 
built. They have left behind them traditions of which 
traces are found in a large number of engines exported 
to various countries of Europe. 



GENERAL DESCRIPTION. 

The Walschaert valve gear differs from the Stephen- 
son link motion in that it requires for each cylinder but 
one eccentric or its equivalent, to insure the movement of 
the valve, and the proper distribution of the steam for 
both forward and backward motion. The elimination of 
the heavy eccentrics and their connections relieves the 
axle of an appreciable portion of its dead weight. It also 
makes it possible to place the gear outside the driving 
wheels in a more accessible position, where the parts can 
readily be oiled, inspected and repaired. 

While it may not be possible to adjust the valve as 
readily with the Walschaert gear as with the Stephenson 
motion, for the reason that the parts and connections are 
not as susceptible to change, it is not as liable to become 
disarranged, and if correctly designed and fitted up will 
give accurate results with less difficulty in application 
and greater economy in construction. 

Equal cut-offs in both ends of the cylinder are more 
easily secured than with the Stephenson motion, and the 
play of the engine on its springs has practically no influ- 
ence on the steam distribution. 

In the Walschaert valve gear the operating eccentric 
is secured to the driving axle either directly or by a re- 
turn crank from one of the crank pins. 

The position of this eccentric or crank is such as to 
give the proper valve travel, the throw corresponding 
with the movement of the valve irrespective of its lap 
and lead; the angular advance of the eccentric being o°. 

The link is of any convenient form and is usually 

10 



GENERAL DESCRIPTION 11 

pivoted to a support on the engine frame or suspended 
from the guide bearer. The trunnion is rigid and there 
is no chance for twisting strains. The link is actuated 
by the eccentric rod which is commonly attached to its 
lower extremity. The sliding block in the link is secured 
to one end of the radius rod. The raising or lowering 
of this rod by means of the reversing shaft, shifts the 
block from one end of the link to the other above or 
below the pivotal connection ; this reverses the move- 
ment of the valve with relation to that of the eccentric. 

In many cases the gear can be so designed that the 
motion is transmitted from the eccentric to the valve stem 
in one vertical plane so that practically all of the pins can 
be put in double shear, and all tendency to twist the valve 
motion is avoided. In some cases (see Fig. n) it is neces- 
sary to have the eccentric and the valve stem in different 
vertical planes. In such cases some form of rock shaft 
is necessarily employed to transfer the motion from one 
plain to the other and give the required solidity to the 
gear. It is sometimes urged against the Walschaert mo- 
tion that it requires more moving parts than the Stephen- 
son. This is, however, offset by the better opportunities 
for solid construction and ready inspection and adjust- 
ment. 

The end of the radius rod opposite the link is attached 
to a combining lever, the function of which is to give 
the required lap and lead to the valve. The lower end 
of this lever is connected to and travels with the cross- 
head, while to the upper end is secured to both the valve 
rod and the radius rod, one being placed above the other. 
The point at which the radius rod is attached to the 
combining lever becomes a fulcrum. The relative move- 
ment of the two ends of the lever must be such that the 
full movement of the crosshead imparted to the lower 



12 THE WALSCHAERT VALVE GEAR 

end of the lever will give a movement of the upper end 
equivalent to twice the required lap plus the lead. 

Under ordinary conditions with steam chest valves 
having outside admission, the connection or fulcrum be- 
tween the radius rod and the combining lever is placed 
below the valve rod connection. With valves having 
inside admission, this fulcrum is usually placed above 
the valve rod connection as shown in Fig. 3. 

The link should have a radius equal to the length of 
the radius rod. If this is so it will be seen that when the 
engine is on the dead center the link block can be moved 
from end to end of the link without altering the position 
of the valve with relation to the ports and the lead will 
be constant. 

As any variation in the length or relative position of 
the link, the radius rod, and the combining lever or its 
connections, will necessarily change the resulting move- 
ment of the valve; it is absolutely essentia!, first, that 
the motion shall be correctly designed and plotted, and 
second, that the detail parts shall be accurately con- 
structed according to the diagram. With these two 
points assured the adjustment of the gear on the loco- 
motive is quite simple. The dead center marks on the 
rim of the driving wheel and the port tram, marks on the 
valve stem are found in the usual manner. After con- 
necting the gear any slight variation which may occur 
between the forward and backward position of the valve 
can be adjusted by lengthening or shortening the eccen- 
tric rod. 

The size and arrangement of parts in a modern loco- 
motive make it difficult for an engineer to properly ex- 
amine the eccentrics and link motion when the engine 
is on the road, and breakdowns are more frequent on 
this account. The conditions of service also tend to 



GENERAL DESCRIPTION 



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14 THE WALSCHAERT VALVE GEAR 

make it more and more difficult for the engine man to 
give the close inspection and care which is demanded in 
other branches of engineering service with high speed 
machines. Stationary engine practice may serve as a 
guide to those responsible for the successful operation 
of locomotives, which are even to a greater extent than 
stationary engines, high speed machines. With the 
Walschaert valve motion only a single eccentric or its 
equivalent is necessary for each valve. As usually con- 
structed it is found more convenient to substitute a re- 
turn crank, thus reducing the pin bearings to the smallest 
possible diameter, so that they may be readily lubricated, 
and, owing to the small amount of work they have to do, 
give satisfactory service and absolute freedom from 
heating. 

So far as the distribution of steam in the cylinders is 
concerned, the constant lead, which is a feature of this 
motion is not considered objectionable, and it has some 
distinct advantages. Under such conditions it is possible 
to determine the amount of lead the engine should 
have at the most economical point of cut-off. This point 
determined, and so designed, it cannot be altered by any- 
one in the shops or roundhouses. Another advantage is 
that it prevents valve setters from attempting to produce 
results by moving the eccentrics into improper relations 
one to another. 

The constant lead of the Walschaert motion prevents 
the sealing of the cylinders by the piston valve when the 
piston is at the end of its travel or approaching it. 
Whereas with the link motion, either by derangement or 
excessive wear, the valve laps the ports at the end of the 
stroke, thus causing excessive compression and many 
other troubles. 



GENERAL DESCRIPTION 



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16 THE WALSCHAERT VALVE GEAR 

Another feature of the motion which appeals to the 
engineer is the ease of handling the reverse lever when 
the locomotive is running at a high rate of speed. 

Table i. — General Dimensions. 

Freight Locomotive — Mallet Compound, with Walschaert 
Valve Gear Built for Baltimore & Ohio Rail- 
road by the American Locomotive Company. 
Gauge of track, 4 feet Sy 2 inches 

Loaded Weights 

On driving wheels 334,500 pounds 

Total engine 334>50° pounds 

Tender 143,000 pounds 

Wheel Base 

Driving 10 feet and 10 feet 

Total of engine 30 feet 8 inches 

Total of engine and tender 64 feet 7 inches 

Cylinders 

Diameter 20 inches and 32 inches 

Stroke of piston 32 inches 

Valves H. P. piston, L. P. slide 

Wheels 

Diameter of driving wheels, outside 56 inches 

Diameter of tender wheels 33 inches 

Journals — Diameter and Length* 

Driving 9x13 inches 

Tender . 5 V2X10 inches 

Type, 0660 C 334, Mallet Articulated 



general description 17 

Boiler. 

Type Straight Top, Radial Stay 

Outside diameter at front end 84 inches 

Length of fire-box, inside 108 inches 

Width of fire-box, inside 96 inches 

Number of tubes 436 

Diameter of tubes 2 X 4 inches 

Length of tubes 21 feet 

Working pressure per square inch 235 pounds 

Heating surface in tubes 5.366.3 sq. feet 

Heating surface in fire-box . 219.4 sq. feet 

Total heating surface 5 ,585.7 sq. feet 

Grate area 72.2 sq. feet 

Tender Capacity 

Water 7,000 gallons 

Fuel 15 tons 

Clearance Limitations 

Height of stack above rail 15 feet 

Width 10 feet 5 inches 

Length over all 79 feet 6 T / 2 inches 

Maximum tractive power, 71,500 pounds working com- 
pound. 



DETAILS OF CONSTRUCTION. 

Having presented a general description of the Wals- 
chaert gear, together with a few of the advantages to be 
derived from its use, it is now in order to consider it 
more in detail. Valve gear has not improved propor- 
tionately to the improvement of other factors in connec- 
tion with locomotive development during the past twenty- 
five years, and it is certainly to the interest of engine 
men, machinists, engineers, and all others connected with 
the construction, maintenance, and operation of loco- 
motives, to familiarize themselves with a valve gear that 
offers so many mechanical and structural advantages 
over the Stephenson motion as does the Walschaert gear. 
The facts are that this valve gear has become almost a 
necessity in modern locomotive practice, owing to con- 
ditions created by the demands of transportation. 

The Walschaert valve gear has long been in use on the 
main line locomotives in Europe, about 90 per cent of 
the engines there being equipped with it, and American 
designers now turn to this gear to enable them to meet 
present and future conditions. The principal reasons 
given by the builders of American locomotives for ap- 
plying the Walschaert gear to their engines, especially 
those of the larger types, may be summed up as follows : 

(1) Accessibility. There is not room enough for the 
Stephenson gear under a very large passenger or freight 
locomotive. The eccentrics are crowded, and proper in- 
spection, not to speak of proper care, is difficult, except 
over a pit. Valve gear to be properly maintained must 
be accessible for inspection and lubrication. The accessi- 
bility of Walschaert gear should reduce engine failures. 

18 



DETAILS OF CONSTRUCTION 19 

(2) Weight. A saving of 1,745 pounds is possible 
by using the Walschaert gear, in the case of a very heavy 
passenger locomotive (see table 2). Stephenson gear, 
•weighing as much as two tons, is far too heavy to be 
•satisfactorily reversed twice in every revolution on fast 
running locomotives. 

(3) Directness. Walschaert gear transmits the mov- 
ing force to the valve in very nearly straight lines, avoid- 
ing the springing and yielding of the rocker arms, rocker 
shafts and transmission bars, which cannot be avoided 
in these parts of the Stephenson motion, even if they are 
made very heavy. 

(4) Permanence of Adjustment. The advantage of 
permanence of adjustment lies with the valve gear which 
has no large eccentrics. All connections in the Wal- 
schaert gears are made with pins and bushings, which 
are designed specially to resist wear. 

(5) Wear. Large eccentrics, besides occupying too 
large space, wear unevenly, and lubrication is difficult 
with the high surface velocities of the largest sizes. With 
hardened pins and hardened bushings the Walschaert 
gear has an important advantage in maintenance. 

(6) Smooth Operation. Stephenson links, under the 
influence of two eccentrics, move through wide angles, 
resulting in a wedging action of the link block, which 
strains the gear when working hard, and produces lost 
motion. Walschaert links oscillate through smaller 
angles, producing less lost motion. The effect of this 
angularity of the links is plainly discernible on the test- 
ing plant. 

(7) Frame Bracing. The removal of the valve gear 
from between the driving wheels facilitates bracing the 
frames of the locomotive laterally. 



20 THE WALSCHAERT VALVE GEAR 

The great saving in weight of the various parts of the 
Walschaert valve gear, as compared with the Stephenson 
link motion is shown in table 2, 

It may be assumed that the student is familiar with the 
meaning of the terms lap, lead, and cut off, when used in 
connection with the operation of the valve, also that the 
principles governing the action of outside admission 
valves, as compared with those of inside admission, are 
thoroughly well understood, therefore it will not be neces- 
sary to occupy space by an explanation of these matters. 

In the construction of the Walschaert gear the desired 
travel of the valve, the lead and the maximum cut-off 
which determines the lap of the valve, are selected. The 
stroke of the piston being given, the combination lever 
is proportioned so that a motion equal to the lap and lead 
is given to the valve when the crosshead is moved from 
one end of the stroke to the other. The link may be made 
of any approved design, and is so located that the radius 
bar will have a length of at least eight times (ten or 
twelve times is better) the travel of the link block, and 
the radius of the link should be equal to the length of 
the radius bar. 

For outside admission valves the radius bar is attached 
to the combination lever between the valve stem and the 
crosshead connections, and for inside admission (piston 
valves) it is attached above the valve stem. The fulcrum 
of the link should lie as nearly as practicable upon a line 
drawn through the union of the radius bar and combina- 
tion lever, parallel with the center line of the valve stem. 
The suspension point of the lifter should have a locus 
w T hich causes the link block to travel as nearly as prac- 
ticable on a chord of the arc described by any point of the 
link wherever the block happens to be when the link is 
swung into one of its extreme positions. This is most 



DETAILS OF CONSTRUCTION 



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22 THE WALSCHAERT VALVE GEAR 

closely approached by a lifter through which the radius 
bar slides, and does not swing with the link. A properly 
suspended hanger will accomplish practically the same 
result, though the slip of the link bar will be somewhat 
more in the back than in the forward motion, but as the 
suspension point cannot be made to follow the theoretical 
locus, it should be made to do so as nearly as possible by 
favoring the position of the most commonly used cut-offs. 
In locating the longitudinal position of the link fulcrum, 
consideration should also be given to the length of the 
eccentric rod, which should have a minimum length of 
three and one-half times the eccentric throw, and should 
be made as long as circumstances will permit, with an 
approximately equal length of the radius and eccentric 
rods. The point of connection between the eccentric rod 
and the link should be as near the center line of motion of 
the main rod as this correction for rod angularities will 
permit, but this is often accompanied with the require- 
ment of excessive eccentric throw. In such cases a com- 
promise must be made to raise this point. The fore and 
aft position of this point relative to the tangent of the link 
arc must also be determined with reference to the angu- 
larity of the eccentric and main rods, so that the link is 
exactly in its central position when the piston is at either 
end of the stroke. The angles through which the link 
swings on both sides of its central position should be as 
nearly as practicable equal, but this is subordinate to 
other conditions. Attention should be paid to the effect 
of the angularity of the main connecting rod upon the cut- 
off, to reduce this to a minimum, this having an effect 
upon determining the locus of the suspension point of 
the lifting link as well as that of the eccentric rod connec- 
tion to the link. 

Walschaert gears should be correctly laid out and con- 



DETAILS OF CONSTRUCTION 23 

structed from a diagram, as the proportions cannot be 
tampered with by experimental changes without seriously 
affecting the correct working of the device. 

The only part capable of variation in length is the 
eccentric rod, which connects the eccentric with the link. 
This rod may be slightly lengthened or shortened, to cor- 
rect errors in location of the link center, from center of 
driving axle which carries the eccentric. 

The eccentric usually assumes the form of a return 
crank on one of the crank pins, and its center is at right 
angles to the plane of motion, viz. : — at ninety degrees to 
a line drawn from the point on the link at which the 
eccentric rod is attached, through the center of the driv- 
ing axle. This eliminates the angular advance of the ec- 
centric, and allows the use of a single eccentric for both 
forward and backward motion. The throw as specified 
must be correctly obtained, and great care taken that the 
position shown in the design be adhered to. The crank 
representing the eccentric is permanently fixed to the pin, 
and the slightest variation will be detrimental. 



METHOD OF LAYING OUT WALSCHAERT 

GEAR. 

Having presented a general outline of the gear, we may 
proceed in determining the more important points neces- 
sary to obtain a successful motion of the valve, and, as 
previously stated, the stroke of the engine is given, and 
the travel and lap and lead of the valve are selected to 
suit a desired cut-off. We have first to find the propor- 
tions of the combination lever. By designating the lap and 
lead with a letter C, the crank Radius with R, the cross- 
head end of the combination lever with L, and the valve 
end of the same with V, we have R : C = L : V, or V = 

CL 

—5— , with the connection F of the radius bar as a ful- 

XV 

crum. The length of the combination lever must be de- 
termined from a height of the valve stem over the piston 
rod and a convenient angle of oscillation of 45 to 50 , 
which should not exceed 6o°. 

We have next to find the required travel of point F, 
Fig. 5, to obtain the desired valve travel, which for con- 
venience sake is taken on one side of the center position, 
or half its total travel in full gear, and which we will 
designate b, when we have : 



x fe x 



RV-c 9 


R+c 


RV-c 2 



for outside admission, and 



b = — — for inside admission valves. 

R — c 

This may be laid out graphically as in Figs. 6 and 7, 
when a is equal to one-half the travel of the valve and R 
and c the same as in the above formulae. 

24 



METHOD OF LAYING OUT GEAR 25 

With the limited amount it is advisable to allow in 
raising or lowering the link block in reversing the mo- 
tion, we can without practical error consider the half 
movement of the link block g to be the same as that of 
point F, and by limiting the angle of the swing of the 
link to a maximum of 45°, we get the raise or depression 

of the radius bar and link block Og = j- , where O 

tan. a, 

is the link fulcrum and d = half the angle of the swing 
of the link. 

The location of the link and eccentric rod connecting 
point K, Fig. 5, cannot be determined with any prac- 
ticable formula, but must, as already stated, be found by 
plotting to meet the requirements of the different cut-offs 
and corresponding crank positions. The same is also the 
case with determining the locus for the suspension point 
P of the lifting link, and in these two locations lies the 
principal success of the gear. 

Note. — The cuts, Figures 5, 6 and 7, are reproduced 
from an article by Messrs. C. J. Mellin and G, L. Fowler 
in Raihvay Machinery, September, 1905. 

Figure 8 illustrates the Walschaert valve gear as ap- 
plied to a heavy freight locomotive, in fact one of the 
largest type belonging to the Lake Shore and Michigan 
Southern Railway. 

This cut will serve to show in a graphic manner the 
location of the various connections of the valve gear, and 
piston valve. The combination lever is shown in its cen- 
tral position and it will be noticed that in this position the 
lower connection, m (see Fig. 5), is in line horizontally 
with point n, the crosshead connection. The vertical 
height of these two points relative to each other slightly 
influences the port opening. The cross section through 



26 



THE WALSCHAERT VALVE GEAR 




< 
H 

O 

H 

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W 
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ft 

o 

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O 

Eh 
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METHOD OF LAYING OUT GEAR 



2? 



cylinder and valve shown in Fig. 8 will give a clear idea 
of the action of the valve and gear. 

Figure 9 is an outline diagram of the Walschaert valve 
gear as applied to a compound locomotive, and serves to 
show the adaptability of the gear to any type of loco- 
motive and all conditions of service. 



In 



Cr 



- c i 



FIGURE 6. 



But, it is evident that a correct design of the Walschaert 
valve gear can only be laid out by a skilled draughtsman, 
and in the adjustment and maintenance of the gear the 
greatest care is required, that all parts should preserve 



l«~ 



•C-JJ 



J 



FIGURE 7. 



their original forms and locations, and this should be 
checked by verifying the valve events through turning 
the main driving wheels before the locomotive goes into 
active service. 



28 



THE WALSCHAERT VALVE GEAR 




METHOD OF LAYING OUT GEAR 



29 




30 THE WALSCHAERT VALVE GEAR 

The Walschaert motion, as usually constructed, does 
not lend itself as freely to adjustment as does the 
Stephenson motion with independent eccentrics, and for 
this reason it is not as liable to get out of adjustment. It 
must be correctly laid out in the design and correctly 
fitted up. The importance of this cannot be overesti- 
mated. The various points must be carefully plotted in 
order to give the best results in the combination move- 
ment of the parts of the motion. The movements of the 
motion involve such complications in plotting as to render 
the complete plotting of all, too laborious for every new 
design, and for this reason the use of an adjustable model 
is very desirable in designing this gear. However, with 
complete knowledge of the nature of the gear, simple 
methods and formulae may be used to determine the loca- 
tions of the various points covering the motion. One ob- 
ject of this description is to avoid the necessity of a model 
except to verify the results. 

To entirely overcome the irregularities inherent in 
all motions transformed from circular into lineal, cannot 
for practical reasons be expected, but the errors may be 
reduced to such an extent that they do not affect either 
the power or economy of the locomotive. This remark 
is made to forestall the inference that the accuracy of 
the Walschaert motion as to the cut-off points is not su- 
perior to the Stephenson motion when the latter is turned 
out of the shop. 

The chief point of difference between the Walschaert 
and Stephenson motions is that the former gives to the 
valve a constant lead at all cut-offs, whereas the latter 
produces an increase of lead which becomes excessive at 
short cut-offs. 



DETAILS OF ADJUSTMENT. 

In setting the Walschaert valve gear it must be borne 
in mind that two distinct motions are in combination, viz. : 
the motion due to the crosshead travel, and the motion 
due to the eccentric throw. 

The crosshead motion controls the lead, by moving 
the valve sufficiently to overcome its lap, by the amount 
of lead in both front and back positions. The eccentric 
throw controls the travel and reversing operations. It 
will be seen that the movement due to the eccentric, with- 
out the crosshead motion, would place the valve centrally 
over the ports when the piston is at the extreme end of 
the stroke. The combined effect of these two motions, 
when the parts are properly designed, gives the required 
movement of the valve, similar to that obtained by the use 
of a stationary link. To reverse the engine, the link block 
is moved from end to end of the link, instead of moving 
the link on the block. This operation is accomplished 
by means of a reversing shaft connected with a reversing 
lever in the cab. 

Walschaert gears should be correctly laid out and 
constructed from a diagram, as the proportions cannot 
be tampered with by experimental changes without seri- 
ously affecting the correct working of the device. 

The only part capable of variation in length is the ec- 
centric rod, which connects the eccentric with the link. 
This rod may be slightly lengthened or shortened, to cor- 
rect errors in location of the link center, from center of 
driving axle which carries the eccentric. 

31 



32 



THE WALSCHAERT VALVE GEAR 











a 
o 

> 

H 

o 









DETAILS OF ADJUSTMENT 33 

When the engine is assembled, the throw of the eccen- 
tric should be checked up by the specifications, and any 
error should be reported at once, in order that the mis- 
take may be rectified by either correcting the position of 
the eccentric, or by a change in the design of the other 
parts to compensate for the error. 

The lap and lead being determined by the proportion of 
the arms of combination lever, and the stroke of the pis- 
ton, the amount is found by turning the engine from one 
dead center to the other in any cut-off position. 

Mr. Carl J. Mellin of the American Locomotive Com- 
pany furnishes six very useful hints relating to the ad- 
justment of the Walschaert valve gear as follows: 

i. The motion must be adjusted with the cranks on 
the dead- centers by lengthening or shortening the eccen- 
tric rods until the link takes such a position as to impart 
no motion to the valve when the link block is moved from 
its extreme forward to its extreme backward position. 
Before this change in the eccentric rod is resorted to, the 
length of the valve stem should be examined, as it may 
be of advantage to plane off, or line under, the foot of the 
link support which might correct the lengths of both rods 
or at least only one of these should need to be changed. 

2. The difference between the two positions of the 
valve on the forward and back centers is the lap and lead 
doubled, and cannot be changed except by changing the 
leverage relations of the combination lever. 

3. A given lead determines the lap, or a given lap 
determines the lead, and it must be divided for both ends 
as desired by lengthening or shortening the valve spindle. 

4. Within certain limits this adjustment may be made 
by shortening or lengthening the radius bar, but it is de- 
sirable to keep the length of this bar equal to the radius 



34 THE WALSCHAERT VALVE GEAR 

of the links, in order to meet the requirements of the 
first condition. 

5. The lead may be increased by reducing the lap, 
and the cut-off point will then be slightly advanced. In- 
creasing the lap introduces the opposite effect on the cut- 
off. With good judgment these quantities may be varied 
to offset their irregularities inherent in transforming 
rotary into lineal motions. 

6. Slight variations may be made in the cut-off points 
as covered by the previous paragraph, but an independent 
adjustment cannot be made except by shifting the loca- 
tion of the suspension point, which is preferably deter- 
mined by a model. 

The Baldwin Locomotive Company supplies the fol- 
lowing u Special Instructions" for guidance in the erec- 
tion of the Walschaert valve gear and setting the valves : 

1. Check carefully the dimensions of the following 
parts, rejecting any that are not exactly to drawing: 

a — Valve. 

b — Valve stem. 

c — Valve crosshead or slide. 

d — Combining lever. 

e — Crosshead link. 

f — Link radius rod. 

g — Reverse link. 

h — Location of combining lever on crosshead. 

k — Length of eccentric crank. 

2. Check eccentric throw to see that it is exactly as 
specified. 

3. Re sure that guide bearer is correctly located from 
center of cylinder, as the reverse link is usually attached 
to it, and variations in the location of the link cannot 



DETAILS OF ADJUSTMENT 



35 



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36 THE WALSCHAERT VALVE GEAR 

be allowed. If the link is attached to separate crosstie, 
similar precautions must be taken to insure its correct 
location. 

4. Exercise great care in the location of the link so 
that the trunnion center is exactly to dimensions from the 
center of cylinder. 

5. See that the reverse shaft center is correctly lo- 
cated to dimensions given, and that the lifting arm and 
link are of the exact lengths as specified. 

6. Connect crosshead gear to valve, and radius rod to 
link, without connecting eccentric rod to link. 

7. Hook up radius rod to exact center of link, and 
then revolve driving wheels, seeing that crosshead gear 
gives correct lead as specified for both front and back 
admission ports. 

8. Connect link to return crank by eccentric rod, and 
obtain full travel front and back, and in both forward 
and backward motions, correcting any errors by length- 
ening or shortening eccentric rod, as previously noted. 

The valves may now be considered as definitely set, 
and may be tested to any cut-off points in the usual man- 
ner. A simple additional check should be made as fol- 
lows : set one side of the engine so that the piston is at 
its extreme forward position in the cylinder, and check 
the lead on the admission port. 

In this position it should be possible to move the link 
block through its entire travel in the link, without in any 
way disturbing the movement of the valve. 

This operation should then be reversed, and the other 
side of the engine similarly tried with the piston located 
at its extreme backward position in the cylinder. . 



TYPES OF LOCOMOTIVE VALVES. 

The adaptability of the Walschaert valve gear to the 
many and varied conditions in locomotive practice has al- 
ready been commented upon, and will be referred to 
again later on. 

A short space will now be devoted to the leading types 
of locomotive valves and their operation. The plain old 
time D slide valve still retains a large place in the steam 
distribution of locomotives, notwithstanding the disad- 
vantages attending its use. 

The principal objection to the use of the D slide valve 
is the large amount of friction caused by the action of the 
steam pressing the valve against its seat, and inventors 
have racked their brains for many years in efforts to pro- 
duce a valve that would work without friction, and at 
the same time give a correct distribution of the steam to 
and from the cylinders. 

The piston valve, while practically balanced, owing 
to the pressure of the steam acting upon each end, is, 
nevertheless, not a perfectly balanced valve unless the 
valve rod extends through both ends of the valve cham- 
ber, and this necessitates an extra gland and set of rod 
packing. In order to more clearly illustrate this idea, 
reference is made to Figs. 12 and 13. Fig. 12 shows a 
plain D slide valve, and it will be noticed that the full 
pressure of steam in the valve chest acts upon the back of 
the valve. Of course there is a certain amount of back 
pressure from the steam port and exhaust port that tends 
to overcome the direct pressure ; still there is an enor- 
mous strain on the valve gear that is required to move a 
valve under such conditions. Fig. 13 shows a solid pis- 

37 



38 



THE WALSCHAERT VALVE GEAR 



ton valve with outside admission, being thus identical in 
action with the D valve. 

No valve rod is shown in either cut, but it will easily 
be seen that with the valve rod attached to but one end 
of the piston valve the area of that end will be decreased 




FIGURE 12. 



just so much, and the valve will be unbalanced by an 
amount equal to the sectional area of the valve rod, but 
this amount is so insignificant that builders very seldom 
add the extended valve rod, and so the piston valve may 



STEAM 




v j 




STEAM 




^exhaustN 









FIGURE 13. 



be considered as balanced, the only friction being that 
due to the weight of the valve and the friction of the 
packing rings when the valve is fitted with them. In 



TYPES OF LOCOMOTIVE VALVES 39 

some types of piston valves the live steam is admitted 
inside, between the heads, as shown in Fig. 14, and the 
exhaust passes out around the ends, but the same prin- 
ciple of balancing is retained as with the outside admis- 
sion type, for the reason that the pressure is applied be- 
tween the ends of the valve instead of on the outside as 
with the other type. The sketches here given do not 
show the valves in their true proportions, being merely 
used to illustrate the principle upon which the piston 
valve works. In practice the valve is made as long as 
possible, in order that the ports leading to the cylinder 
may be shortened to the minimum. 

Another type of piston valve is shown in Fig. 15. This 
valve is made hollow for lightness and has packing rings 
at each end to prevent the steam from passing into the 
ports until at the proper moment. The edges of these 
packing rings control the admission of steam to the ports 
in the same manner as do the edges of the D valve, and 
when the valve is one of outside admission it is set in 
the same manner as the D valve is. But if admission is 
from the inside, as shown in Fig. 16, the movement of 
the valve is reversed, as is the method of setting also. 
As it is very essential that the packing rings at each end 
of a piston ^alve be steam-tight, a certain element of 
friction is introduced in this manner. In the larger num- 
ber of cases where piston valves are used, central or in- 
side admission is the rule, a great advantage of this type 
over outside admission valves being that the larger por- 
tion of the cooling surface of the valve chamber is re- 
served for the exhaust steam. Another advantage is that 
of having only exhaust pressure against which to pack 
the valve rods, and make the joints for the heads of the 
valve chamber. 



40 



THE WALSCHAERT VALVE GEAR 



In taking charge of an engine having piston valves, 
an engineer should always first "look her over^' and note 
the positions of the eccentric with relation to the crank 
pin. He should also take a look at the rocker shaft if 



/ 




V LIVE J 




i 




^STEAM^ 













■^^■3 



FIGURE 14. 



there is one. He will then be able to satisfy himself as 
to whether the valves have outside or inside admission, 
a very important thing to know in case anything should 
happen out on the road that necessitated resetting of one 




FIGURE 15. 



or both of the valves to enable him to bring his engine 
home. As before stated, the movement of a piston valve 
having outside admission is precisely the same as that 



TYPES OF LOCOMOTIVE VALVES 



41 



of a D slide valve, but it is well to note the fact that 
while the great majority of engines fitted with D slide 
valves have indirect valve gear, still there are some in 
which the motion is direct. For the guidance of the en- 
gineer in such cases, the following four simple rules are 
here given : 

Rule i. If the eccentric and crank pin are together, 
that is, on the same side of the driving shaft, and there 
is a rocker arm that reverses the motion, the valve has 
outside admission, indirect. 




FIGURE 16. 



Rule 2. If the eccentric and crank pin are together 
and there is no rocker arm, but direct motion, the valve 
has inside admission, direct. 

Rule 3. If the eccentric and crank pin are on oppo- 
site sides of the driving shaft, and there is a rocker arm 
to reverse the motion, the valve has inside admission, 
indirect. 

Rule 4. If the eccentric and crank pin are on opposite 
sides of the shaft, and there is no rocker arm to reverse 
the motion, the valve has outside admission, direct. 

The American Balanced Valve Company of Jersey 



42 THE WALSCHAERT VALVE GEAR 

Shore, Pa., are the makers of a new type of piston valve, 
which they term "The American Semi-Plug Piston 
Valve." This valve, a description of which is here 
given, has performed very efficient service since its in- 
troduction, and it appears destined to occupy a promi- 
nent position in locomotive work in the future. 

Referring to Fig. 17, an internal admission valve is 
shown. The inner sides of the two snap rings, 1-1, are bev- 
eled. The outer sides of the snap rings are straight and 



12 3 2 1 




FIGURE 17. 

fit against the straight walls of the valve spool. Against 
the beveled sides of the snap rings, solid, uncut, non- 
expansible wall rings, 2-2, fit. Their inner sides are 
beveled at a greater degree of angle than their outer 
sides, which fit the snap ring. 

In between the two wall rings is placed a central 
double tapered snap ring, 3. This ring is properly lapped, 
and is put in under tension, thus holding the wall rings 
apart, putting a slight grip on the snap rings laterally. 
Thus applied, the action is as follows: When steam is 



TYPES OF LOCOMOTIVE VALVES 43 

admitted to the steam chest, or central portion of the 
valve, it passes through openings in the spool to the space 
beneath all of the rings, and acts upon the central wedge 
ring direct, giving it a lead of the snap rings in action, 
and forcing the wall rings against the sides of the snap 
rings, so that prevention of their excessive expansion is 
positive. The snap rings are thus expanded against the 
casing just enough to make steam-tight contact, and the 
central ring grips them there, and they are prevented 
from further expansion. This is demonstrated by with- 
drawing the valve from the valve chamber while under 
steam until the first ring in the spool is entirely out of 
the cylinder, when no increase in the diameter of the 
snap ring can be observed. It can then be pushed back 
into the cylinder again. It will readily be understood 
how easy it is to prevent further expansion of the snap 
ring by the pressure underneath it, when the degree of 
angle of the bevel on the inside of the snap ring is con- 
sidered. By making this degree greater, the power of 
the central wedge ring would be sufficient to decrease the 
diameter of the snap ring, closing it away from the valve 
chamber. Therefore it appears that this valve has all the 
advantages of the plug valve, without the drawbacks of 
the plug valve, and it has all the advantages of the snap 
ring valve, without the drawbacks of the snap ring valve, 
because it is practically a plug that does expand and 
take care of itself, not only for the difference in contrac- 
tion and expansion, but also for wear ; yet the plug is not 
so rigid as to knock a cylinder head out before relieving 
the water from the cylinder, and yet it is absolutely ad- 
justed to the diameter of the casing at all times, and is 
held there and allowed to get no larger during its work 
under pressure. The rings are so lapped that they are 
steam-tight from all directions, and the bevel lap joint 



44 



THE WALSCHAERT VALVE GEAR 




TYPES OF LOCOMOTIVE VALVES 45 

maintains unbroken steam and exhaust lines at the edge 
of the ring. 

Fig. 1 8 further illustrates the construction of this 
valve, giving end and sectional views of the different 
parts. A common defect of snap ring piston valves is 
that the steam pressure gets under the rings, and ex- 
pands them against the casing with the full force of the 
chest pressure, thus causing excessive friction, while at 
the same time the cage is worn unevenly by the valve 
working at short cut-off and over the ports. Under such 
conditions, steam-tight joints soon become leaky, and 
the leakage rapidly increases as the wearing goes on. 

A piston valve, in order to give efficient steam-tight 
and durable service, should automatically regulate the 
frictional contact of the rings against the cage, and keep 
the cage perfectly true. 

Many locomotives are equipped with piston valves of 
different types, but the internal admission valve appears 
to be the favorite. 

One of the advantages the piston valve possesses over 
other forms of slide valves is that it may be made long 
enough to bring the two faces or working edges near 
the ends of the cylinder, thus greatly reducing the clear- 
ance between the valve face and the piston. 

The term balanced valve, as used in this connection 
with reference to locomotive practice, is meant to include 
all balanced valves except those of the piston type. As 
stated at the beginning of this section, there have been 
many different kinds of balanced valves applied experi- 
mentally to the locomotive, by inventors in their efforts 
to reduce the friction between the face of the valve and 
its seat. 

A few of the more meritorious of these will be de- 



46 



THE WALSCHAERT VALVE GEAR 



scribed and illustrated. Fig. 19 shows the Jack Wilson 
High Pressure Valve. 

This valve has two faces. One face moves on the valve 
seat proper, and the other face moves in contact with the 
face of the balance plate. Both faces are the same, and 
it has no crown, but is open throughout. The face of the 
balance plate is an exact duplicate of the cylinder valve 
seat, and set in alignment therewith, therefore whatever 
conditions exist on one face of the valve must necessarily 
exist on the other face. 




FIGURE 19. 



The walls of the valve are provided with ports which 
pass from face to face of the valve. The balance plate, 
Fig. 20, contains balancing cones M C and P C (main 
cone and port cone), and two centering ring grooves, that 
register with similar grooves in pressure plate. 

The face of the balance plate, Fig. 21, is an exact du- 
plicate of the cylinder valve seat and forms a second 
valve seat against which the valve operates in unison 
w T ith its operation on the cylinder valve seat, the second 
seat being held by means of the centering rings CR, Fig. 
22, in exact alignment with the valve seat proper. The 
back or opposite side of the balance plate, Fig. 25, con- 



TYPES OF LOCOMOTIVE VALVES 



47 



tains the following cones: one large or main cone (MC) 
and two small or port cones (PC) on the interior of the 




FIGURE 20. 





















r- 












D D 
DD 




c 

o 
















a d 

DD 








"~~^ 









FIGURE 21. 



main cone, and on which the packing rings are placed, 
which forms the balancing feature to the valve, and the 



48 



THE WALSCHAERT VALVE GEAR 




O 



TYPES OF LOCOMOTIVE VALVES 



49 



centering ring cones. The balance plate is provided with 
wings (BW) which fit 1-16 inch loose into the wings of 
the pressure plate (or into the steam chest itself), pre- 
venting excessive movement of plate. Taper or beveled 
packing rings set on the cones form joints against the 
pressure plate. 






FIGURE 23. 



Pressure Plate. The pressure plate is made either 
as a part of, or separate from the chest cover. In the 
type of valve here referred to, the pressure plate is made 
separate (see Figs. 23, 24 and 25) and is provided with 
wings (W) which are machined to fit snugly into the 
steam chest ; the chest being first centered with the valve 
seat by fitting over lugs on the cylinder, or by dowel pin, 
and machined at the top to receive wings (W) of the 



50 



THE WALSCHAERT VALVE GEAR 



pressure plate. Into the face of the pressure plate two 
grooves are cut with either straight or taper walls and 
w T hich register correctly with the corresponding grooves 
in the balance plate ; these are called centering ring 




FIGURE 24. 



grooves and into them two centering rings (CR) are 
placed, slightly under tension. Under normal conditions 
these steel rings hold the balance plate in alignment with 
the valve seat, but under abnormal conditions, such as 




FIGURE 25. 



dry valves, the strain will be taken by the wing of the 
balance plate against the wing of the pressure plate, pre- 
venting excessive contraction of the centering rings. 
Against the face of the pressure plate the balancing rings 



TYPES OF LOCOMOTIVE VALVES 51 

form steam joints. The balanced area of this valve is 
changeable, the change taking place automatically, so as 
to correspond with the changed condition of the valve on 
its seat at different points of its travel. 

Referring to assembled cross sectional view, Fig. 22, 
the valve is seen in central position on the seat and the 
upper seat or face of balance plate in position corre- 
sponding with the valve seat. The steam chest is cen- 
tered by machined faces fitting over machined lugs on the 
cylinder; on old power, dowel pins are used. The chest 
has finished strips at top into which the finished ends of 
the wings of the pressure plate (W) fit snugly, thus in- 
suring the central position of the pressure plate over the 
valve seat. The finished wings of the balance plate (BW) 
fit 1 -16 inch loose between inside faces of the wings of 
the pressure plate, but the balance plate is held perfectly 
central by two steel centering rings (CR). The tops of 
the cones on the balance plate are J /s inch from the face 
of the pressure plate, allowing the balance plate to lift J /s 
inch off from the valve, which affords perfect relief to the 
cylinder while the engine is drifting and for the relief 
of water from the cylinder. This J/s -inch clearance in 
height adjustment must be maintained. The main bal- 
ancing ring (MR) is made the proper diameter to bal- 
ance the valve as great as possible while in its central 
(or heaviest) position, there being just sufficient area left 
on to insure the balance plate being held steam-tight on 
the valve. The interior of the main ring is open to the 
atmosphere through the holes D, which lead to the 
exhaust cavity of the valve. 

The valve is thus balanced so that it will move per- 
fectly easy in its heaviest position, but conditions are 
changed by the opening of a steam port (and at instant 
of cut-off. See Fig. 26), at which time the ordinary 



52 



THE WALSCHAERT VALVE GEAR 




TYPES OF LOCOMOTIVE VALVES 53 

slide valve is subjected to the upward pressure of the 
steam in the cylinder port, and if properly balanced in 
central position would, at this position, be thrown off its 
seat, but in this valve the port pressure (whatever it may 
be) has free access to both sides of the valve by reason 
of the passages through the valve to the port in the face 
of the balance plate which corresponds with the cylinder 
port; therefore the pressure in the port has no effect 
whatever upon the valve, it being on both sides of the 
valve face of equal area, and pressure is, therefore, equal- 
ized so far as the valve is concerned, but the pressure in 
the port of the balance plate would lift the plate off from 
its seat on the valve if it was not also equalized, or an- 
nulled ; therefore a port ring, PR, of proper area to bal- 
ance this pressure, is placed over each port in the inside 
of the main ring on the top of the balance plate and is 
open to the port through passage F, Fig. 22, so that a 
pressure equal to that in the steam port is always on both 
sides of the balance plate, as well as on both sides of the 
valve, and the port pressure is rendered inoperative on 
the valve or on the balance plate. Communication from 
the cylinder port, through the valve and through the bal- 
ance plate to the interior of the port ring, PR, cannot be 
shut off at any time, but is maintained throughout the 
travel of the valve. Therefore the same pressure that is 
in the port at any given time is also on both sides of 
valve and pressure plate in the same area, and the port 
pressure is, therefore, not considered in figuring the main 
balance for the valve. 

There is another position of the valve during its stroke 
where the slide valve is subjected to an upward pressure, 
or pressure against its face, which tends to lift it from its 
seat ; that position is at over-travel of the valve face over 
the valve seat ; this position is shown in Fig. 27, but in 



54 



THE WALSCHAERT VALVE GEAR 




P 

O 



TYPES OF LOCOMOTIVE VALVES 



55 



this valve it will be observed that the top face or back of 
the valve travels out from under the seat of the balance 
plate exactly to the same extent that it over-travels the 
cylinder seat, and pressure is, therefore, equal on both 
sides of that portion of the valve that is over the seat at 
any point of travel. With the main ring balancing the 
valve fully in its central or heaviest position, the port 
ring balancing the port pressure, and over-travel of the 




FIGURE 28. 



valve on its seat being equalized by equal exposure at top 
and bottom, it will be clear that the valve is fully bal- 
anced in all positions of stroke, and is, therefore, avail- 
able for high pressures. 

The Richardson Balanced Valve. This form of 
balanced slide valve, together with the Allen-Richardson 
balanced slide valve, is manufactured by H. G. Hammett 
of Troy, New York, and is largely used on locomotives. 
Figs. 28 and 29 represent transverse and longitudinal 
sections through the center of an ordinary locomotive 



56 



THE WALSCHAERT VALVE GEAR 



steam chest fitted with the Richardson valve. Fig. 30 
shows a plan of the valve, and Fig. 31 is an elevation of 
one end of the packing strips and spring, the only alter- 




FIGURE 29. 



ation being the addition of the balance plate, P'P, Fig. 28, 
and the substitution of a valve adapted to receive the 
packing strips S, S, S, S. 




FIGURE 30. 



It will be noticed in this instance that the balance plate 
is bolted to the cover of the steam chest, but these may 
be cast in a single piece. The four sections of packing 
enclose a rectangular space, R, Fig. 30, which equals in 
its area the total amount of valve surface which is to be 



TYPES OF LOCOMOTIVE VALVES 57 

relieved of excess pressure, the packing strips preventing 
the steam from entering this space, and the small hole, X, 
communicating with the exhaust cavity in the valve, re- 
lieves space, R, from any possible accumulation of pres- 
sure. 

The four packing strips consist of two longer ones, 
which are simply rectangular pieces of cast iron, while 
the two shorter ones, Fig. 31. have gib-shaped ends to re- 
tain them in their proper position. Beneath each 
packing strip a light elliptic spring, shown in 
Fig. 31, is placed, which holds these strips in 
position against the balance plate when steam is 
shut off. 

In operation these different sections maintain 
a steam-tight contact, by a direct steam pressure, 
with the balance plate and with the inner sur- 
faces of the grooves provided to receive them, 
the joint being secured by the abutting of the } 
ends of the two longer sections against the 
inner surfaces of the gibbed sections at the four corners. 

The Allen-Richardson Balanced Slide Valve. 
The Allen valve is designed to at least partly prevent the 
wire-drawing of the steam, when high speeds are main- 
tained with the valve cutting off early in the stroke. 

In the Allen valve, an additional passage for the inlet 
of steam is furnished, as will be clearly seen by referring 
to Figs. 32 and 33. These are transverse and longitu- 
dinal sections through the valve and steam chest, and it 
will be noticed that, when the steam port is open one- 
half inch in the ordinary manner, the port of the cored 
passage is also open to a like extent on the other side of 
the valve ; consequently the effective area of the steam 
port is doubled, and is thus the actual equivalent of a 
single port with a one-inch opening. 



58 



THE WALSCHAERT VALVE GEAR 



The wire-drawing incident to running at high speeds 
with the valve cutting off early in the stroke is thus 
greatly diminished, with a resultant economy of steam 
and fuel. A reduction of wire-drawing carries with it a 




higher average pressure on the piston when working at 
a similar cut-off ; consequently the usual average pressure 
can be maintained with a shorter cut-off, resulting in an 
appreciable economy. While the unbalanced Allen valve, 



TYPES OF LOCOMOTIVE VALVES 



59 



therefore, secures a better and more economical distribu- 
tion of steam, its use entails certain disadvantages. 

On the face of a slide valve, the area of bearing sur- 
face is never sufficient to secure its wearing well under 
a heavy steam pressure ; and this wearing surface is yet 
further reduced in the Allen valve, owing to its internal 
steam ports. This internal passage actually divides the 
valve into two parts, and the steam pressure, acting on 
the outer part, springs and bends its working face below 
that of the internal or exhaust port of the valve. The 
available wearing face is consequently reduced to a space 




FIGURE 33. 



about one-half as wide as the outside lap of the valve, 
and this fully accounts for the rapid wearing of the un- 
balanced Allen valve, and for the trouble and expense of 
constantly refacing valves and seats, and the loss of the 
steam blown through leaky valves quite offsets the ad- 
vantages gained by a reduction of wire-drawing. 

These manifest disadvantages are entirely overcome by 
a proper balancing of the valve, which secures all of the 
advantages of the Richardson device, plus an increased 
steam economy resulting from using the Allen ports. 



60 THE WALSCHAERT VALVE GEAR 

In order to secure the best possible results from the 
employment of the Allen unbalanced valve, its ports and 
bridges should exceed the full travel of the valve, by at 
least one-eighth of an inch, and the radius of the link 
should always be as long as permissible to escape an ex- 
cessive increase of lead when cutting off early in the 
stroke. This latter, however, is prevented with the 
Walschaert valve gear, which gives a constant lead at all 
points of cut-off. 

The Allen valve has made fair progress in American 
locomotive practice, but there is still considerable preju- 
dice against it. This prejudice, we believe, is founded in 
want of experience, or in a mistaken view of what the 
capabilities of the valve are. While this conflict of 
opinion continues to exist, we think that some remarks 
made by Mr. E. M. Herr, superintendent of motive power 
of the Northern Pacific Railway, at a meeting of the 
Western Railway Club, might be studied to advantage. 
The discussion was on lead in the setting of locomotive 
valves, and in this connection he said : 

"With a very long port you can give an engine less 
lead than with a short port, and the kind of valve used 
has also an effect. With an Allen ported valve' you can 
still further reduce the lead and get the same work out 
of the engine. The Allen valve, in my opinion, is a very 
valuable device if rightly used, and I believe that many 
railroad men condemn it because they have not used it 
in just the right manner. You do not get the full 
advantages of an Allen valve if you give it anything like 
as much lead as you w T ould a plain valve. One of the 
principal advantages of an Allen valve is that you can 
reduce the lead and still retain the mean effective pres- 
sure in the cylinder. Of course, there is another advan- 
tage with the Allen valve, and that is the more rapid 



TYPES OF LOCOMOTIVE VALVES 61 

admission of steam into the cylinder, and this enables a 
locomotive at high speeds, with an Allen valve, to very 
much exceed in power the same engine with a plain 
valve. 

In making some tests on the North-Western testing 
plant not very long ago, we showed very conclusively 
that at high speeds a i6x24-inch engine would develop 
more power with an Allen valve than a I7x24-inch engine, 
with practically the same size of driver, would develop 
with a plain valve. In fact, a i6x24-inch engine on a 
certain division, where the ruling grade could be ap- 
proached on a good run, w T as put in freight service with 
17-inch engines, and it did satisfactory work with the 
17-inch engines, pulling over rugged parts of our division, 
until one day the train happened to stop at the foot of 
this ruling grade. That day the engine stalled, and it 
stalled simply because it was not as strong as a 17x24- 
inch engine when pulling at slow speeds. At very high 
speeds it was stronger." 

A cut-off valve for locomotives has been invented by 
Mr. Wm. Goodspeed of Bloomfield, Iowa. This device 
consists of a plain slide valve having no outside lap, a 
loose cut-off plate encircling the valve and moved by the 
action of the valve. 

The following description of the device is given in 
the words of the inventor. We quote as follows : 

"This invention is in the nature of an attachment 
that may be applied to the slide valve of any ordinary 
engine with only slight modifications of the valve, and it 
is especially designed for use in connection with a link 
motion for controlling the speed and direction of rotation 
of the engine. 

"My object in this invention is to provide a valve of 
this class, of simple, strong, durable and inexpensive con- 



62 



THE WALSCHAERT VALVE GEAR 



struction, that may be adjusted, or set to automatically 
cut-off at any desirable point, without employing any 
valve stem, or the like in addition to the ordinary ones 
used. 

"A, further object is to provide a valve in which a 
comparatively large and free induction-port is provided 
when the valve is set to cut-off at a relatively small por- 
tion of the piston's stroke to thereby tend to produce a 
high initial pressure and the consequent increase in the 
efficiency of the engine. 




FIGURE 34. 

"A further object is to provide a valve which may be 
operated so as to admit steam during the entire stroke 
of the piston, so that the entire boiler pressure may be 
used throughout the entire stroke of the piston, when it 
is desired to generate an unusual amount of power, and 
further to provide an engine of this class in which the 
wear upon the valve seat will be extended over a large 
area, and hence the durability of the engine will be 
increased. 

"Fig. 34 shows a top or plan view of the valve mounted 
on its seat within the steam chest. 



TYPES OF LOCOMOTIVE VALVES 



63 



"Fig- 35 is a central longitudinal vertical section on 
line 2, 2 of Fig*. 34. 

"Fig. 36 shows a transverse sectional view through 
the line 3, 3 of Fig. 34, and Figs. 37 and 38 show detailed 
perspective views of parts of the engine and valve to 
illustrate certain details of construction." 




FIGURE 35. 

In describing the cuts, numbers, instead of letters will 
be used to designate the different parts. 

Referring to Fig. 35, 14 is a slide valve which differs 
from the valve of ordinary construction, in that it has 
a diminished inside or outside 
lap, and 15 indicates the valve 
stem passing through the pack- 
ing box, 16, and having a yoke, 
l 7 (Fig. 37), attached to it, 
which encircles the upperportion 
of the valve. 

All of the above mentioned parts are of the ordinary 
construction with the single exception noted. 




FIGURE 3^ 



64 THE WALSCHAERT VALVE GEAR 

The essential novelty in the valve consists of a rectan- 
gular auxiliary cut-off, 18, Fig. 38, having a flat lower 
surface, and having a rectangular opening in its central 
portion. 




FIGURE 37. 



The dimensions of this central opening are in one 
direction, the exterior length of the valve plus the width 
of one of the ports, 12, and in the opposite direction 
exactly the width of the valve. 

In the side pieces of the auxiliary cut-off are the 
longitudinal slots, 19, through which standards or guides 
project, being screwed into the valve seat. 

21 indicates elongated washers having openings 
through which the standards, 20, are passed, so that the 



TYPES OF LOCOMOTIVE VALVES 



65 



under surfaces of the washers may engage the top sur- 
face of the auxiliary cut-off. 

22 indicates spiral springs which are mounted upon 
the standards and compressed by nuts, 23, thus holding 
the washers, 21 , in frictional contact with the auxiliary 
cut-off, 18. 




FIGURE 38. 



This arrangement is for use only when there is no 
steam pressure in the valve chest. 

In practical operation it is obvious that the valve 
proper will be moved a slight distance upon its seat 
before engaging the auxiliary cut-off and when it does 
engage, the cut-off will be moved slightly, that is, when 



66 THE WALSCHAERT VALVE GEAR 

the stroke of the valve is of greater length than the 
width of the ports leading to the cylinder. 

This valve is designed for use only in connection with 
a link motion or other means of regulating the length of 
its travel. 

Assuming that the link motion is set so that the valve 
will cut off at one-quarter stroke, and assuming the valve 
to be in its position for starting, that is, w T ith a small 
lead opening, it is obvious that the first movement of the 
valve will be to open the induction port wide. 

Then the auxiliary cut-off is moved by the valve so 
that the side of the cut-off adjacent to the induction port 
will be moved to partially cover the said induction port. 

Then as the valve starts on its return movement it 
will meet the auxiliary cut-off or that portion thereof 
that is partially covering the induction port at a point 
midway between the sides of the induction port, thus 
cutting off the steam while the valve, has only partially 
covered the induction port, that is, before the full stroke 
of the valve has been made. 

It is obvious that the further movement of the valve, 
that is, to the limit of its travel, and part of the way 
back, will not open the induction port. 

Hence, as Mr. Goodspeed expresses it, "We have a 
one-quarter cut-off with a full opening of the induction 
port, and also a full opening of the exhaust port." 

It is to be understood in this connection that the 
earlier the cut-off the greater is the required length of 
the valve travel. 

When it is desired to work the engine to its fullest 
capacity the valve may be assumed to be in the same 
position as in the former instance, that is, with a small 
lead open. 

Assume, further, that the link motion is set or ad- 



TYPES OF LOCOMOTIVE VALVES 



67 



justed so that the stroke imparted to the valve will be 
only the same as the width of the induction port. 

It is obvious that in this instance the induction port 
will be opened gradually until at the end of the valve's 
stroke it will be wide open. 

In this instance it will be noticed that the auxiliary 
cut-off is not moved, hence the friction of the valve upon 
its seat will be lessened, inasmuch as the area of the valve 
subject to the steam pressure is less than with the ordi- 
nary sized valve having considerable outside lap. 



HALEY S SLIDE VALVE. 

The objects sought to be attained by the use of this 
valve are an increased expansion of the steam after 
cut-off, and the relief of excessive compression. 

It is the invention of Air. J. A. Haley of Fort Wayne, 
Ind. 

It consists in the construction and combination of, 
first, a main valve constructed with shortened face, but 
adapted to actuate an independent valve face, the object 
of which is to supplement the shortened valve face. 

Second, an independent valve face, and, third, devices 
and means whereby during a portion of the travel of the 
main valve, the independent valve face is not operated 
by the main valve, but remains stationary, and thus serves 
to give an increased inside lap at one part of the valve, 
together with increased clearance at the other part alter- 
nately with each stroke of the main valve. 

By the term "independent valve face," is meant a valve 
face which during a given portion of the travel of the 
valve remains stationary and is not moved by the valve 
either directlv or indirectly. 



68 



THE WALSCHAERT VALVE GEAR 



The form of construction of the Haley valve is shown 
in Figs. 39 and 40, where A is the main valve, which 
has portions of its faces cut out in the form of a rabbet, 
thus leaving the faces, a, shortened. 

These rabbets are cut out sufficiently deep to permit 
an independent valve face, B, to be placed underneath 
them and afford room for its independent motion. 

This independent valve face consists of two bars, B, B, 
connected by cross bars, H, which are also placed 
under rabbets on either side of the main valve, A, and 




FIGURE 39. 



its dimensions are such that there will be a space, S, 
between it and the extreme length of the rabbets on the 
inside of the face of the valve, A. 

This frame composing the independent valve face is 
placed on the valve seat within the rabbeted parts of the 
face of the valve, A, and packing, P, is placed above 
the independent valve face, and other packing, p, is 
placed upon the side, in the side rabbets, as shown in 
Fig. 40, for the purpose of preventing steam from passing 
between the valve faces, B and a. 



TYPES OF LOCOMOTIVE VALVES. 



69 



The space S, is for the purpose of, and designed to 
allow a movement of the main valve, A, through that 
distance or space, without moving the independent valve 
face, B. 

Its length is determined by the requirements for inside 
lap, and inside clearance. 




FIGURE 40. 



When the space S has been traversed by the valve A 
moving from n to m, the end of the rabbet impinges 
against the independent valve face B at the port E and 
moves it to the end of travel of main valve A. 

On the return stroke the positions and movements are 
reversed. The faces, A, have chamfers, F, on their inside 
corners for the purpose of permitting the steam to oper- 



70 THE WALSCHAERT VALVE GEAR 

ate against the ends of the independent valve face, B, to 
aid in keeping it alternately pressed against the ends of 
the rabbets for the purpose of preventing any movement 
of B except when actuated by the main valve, A. 

The operation of the device is as follows : When the 
engine is first started the ports are used to their full 
capacity, steam being admitted to the cylinder throughout 
the stroke of the piston, in which case this valve has 
no special operation, but when the stroke of the valve is 
reduced or shortened in order to use steam expansively 
then the following results take place: 

Referring to Fig. 39, let it be assumed that the open- 
ing of the port, C, as shown, is the extreme opening 
for a given point of cut-off. 

At this point the cylinder is therefore taking the full 
amount of steam at such point of cut-off, while the port, 
E, is exhausting at the other end and is open to its full 
extent. 

The width of the exhaust cavity measured on the valve 
seat is determined by the fixed distance apart of the 
inner edges of the two plates, B, B, which form the inde- 
pendent valve face. 

The packings, P, p, prevent the passing of steam be- 
tween the faces, B and a, into and from the exhaust 
cavity. 

The area of space on the valve seat covered by the 
combined valve faces, B and a, varies during the travel 
of the valve. 

When the valve travels, say, on the return stroke 
(see Fig. 39), the faces, B, B, remain stationary until 
the distance, S, has been traveled by the face, a, at the 
end, n ; of the valve seat. 

The inner end of the face, a, then impinges against 
and actuates B. 



TYPES OF LOCOMOTIVE VALVES. 



71 



At this point of travel, and continuing to the end of 
the return stroke, the combined faces, B and a, on the 
end, n, of the valve seat, cover a diminished distance, 
while the faces, B and a, on the other end, m, cover an 
increased distance over the ports and valve seat, the dif- 
ference being represented by the space S. 

Such movement increases the inside lap of the com- 
bined valve faces, B and a, on the end, m, of the valve 
seat, because of the lengthening of the combined valve 
faces, and thereby delays the release of the steam at the 
port, C, thus allowing a greater expansion before exhaust 
takes place. 




FIGURE 41. METZGER'S SLIDE VALVE. 



At the same time while so traveling the distance cov- 
ered by the combined faces, B and a, at the end, n, has 
been reduced correspondingly, and the face, B, has re- 
mained stationary during a portion of the travel, so that 
the closing of port, E, has been delayed, thereby giving 
a free release and reducing the compression in that end 
of the cylinder. 

This increase of the inside lap at the end, m, of the 
valve seat and increased clearance at the opposite end, 
n, is reversed with the reverse travel of the valve. 



72 THE WALSCHAERT VALVE GEAR 



METZGER S SLIDE VALVE. 

The principle involved in the design of this valve is 
practically the same as that in the Haley valve which 
has just been explained. Fig. 41 is a vertical section 
through the valve and shows the construction plainly, 
the object being the same as with the Haley valve, 
viz ; an increased inside lap and free release. 

This form of valve is the design of Mr. Jules P. 
Metzger of Patersom N. J. 



A NEW LOCOMOTIVE VALVE AND VALVE 
SEAT.— C. I. & L. RY. 

There is shown in Fig. 42 a valve and valve seat 
which, while tending in a direction the limit of which 
has probably been tested in another design, is, we be- 
lieve, quite new. It should be understood at first that 
the drawing shows the valve as applied to the ordinary 




FIGURE 42. THE WATKEYS VALVE. 



cylinder casting A A, cored with a steam port on either 
side of the single exhaust port, so that it is necessary 
to put in a false seat, B B, 2 in. thick, and having 
ports suitably arranged for the openings in the valve. 
This makes it necessary also that the steam chest be 
raised 2 in., and accordingly a filling piece 2 in. thick 
is placed under the steam chest. For new work the 

73 



74 THE WALSCHAERT VALVE GEAR 

ports can, of course, be cored in the cylinder casting 
and then the valve seat and steam chest would be of 
the same height as in the ordinary design. 

The valve is shown as central on the seat, and the 
exhaust edges of the steam ports are line and line with 
the inside edges of the valve, so that if it is considered 
that the valve is moving from right to left, the left 
steam port is about to open for exhaust. The double 
exhaust port, however, is covered Y^ in. so that after 
the point where the interior of the valve is opened to 
the exhaust steam, the valve must travel y 2 in. be- 
fore the exhaust port begins to open. The exhaust port 
being double, the area of the port which is uncovered 
by a certain movement of the valve is twice the area 
that would be uncovered were the port single, and a 
freer exhaust must therefore result. The double ex- 
haust port and single steam port would be no better 
than if both ports were single were it not for the ar- 
rangement which makes it possible to open the exhaust 
side of the steam port ^ in. by the time the valve be- 
gins to uncover the exhaust port. The claim made for 
the valve is that the steam can be held in the cylinder 
during a longer portion of the stroke (except for the 
steam which expands into the inside of the valve) be- 
cause when the valve begins to uncover the exhaust 
port the required opening is given by one-half the travel 
of the valve required for the single exhaust port. The 
grooves E E E are cut in the seat to assist lubrication ; 
it is reasoned that they are soon filled with water or oil, 
or a mixture of both, and that the face of the valve is 
coated each time the valve passes over them. The valve 
is the design of Mr. H. Watkeys, Master Mechanic of 
the C. I. & L. Ry. 



A NEW VALVE 



75 



One of the greatest drawbacks to the efficiency of 
high speed locomotives is excessive compression. 

This is a fact that cannot be questioned, and the de- 
vice which will distribute the steam to the pistons, and 
from thence to the atmosphere with the least loss of 
heat, while at the same time smooth running is effected, 
will alwavs meet with favor. 




FIGURE 43 



FARRERS VALVE. 



Xot only does great loss of heat occur through com- 
pression, but another source of loss is excessive clear- 
ance, whereby a needlessly large volume of steam is re- 
quired to fill the space between piston and cylinder head 
at each end of stroke. 

Fig. 43 illustrates the improvement of Mr. Chas. S. 
Farrer of Dunmore, Pa., as applied to the ordinary 
slide valve and the principle of the device is as fol- 
lows: 

Two small holes e, are drilled through each bridge 
in the manner shown. 



76 THE WALSCHAERT VALVE GEAR 

These serve as relief ports, and coincide with the 
grooves cut on the exhaust edges of the valve D thereby 
permitting a portion of the air that is being compressed 
in the cylinder to escape to the exhaust cavity G and 
thence to the stack, thereby reducing compression. 

The advantages obtained by this arrangement are as 
follows : First, a smaller clearance space can be made. 
Second, higher speed can be obtained owing to the 
fact that excessive resistance in the front of the piston, 
in other words back pressure, is obviated, wdien cutting 
off at short points of cut-off, and third, a saving in the 
general wear of the engine, and especially in the wear 
of the valve and seat, by reason of the valve keeping 
dow r n on its seat at all times and not being forced off 
its seat by back pressure caused by excessive compres- 
sion. 

There is therefore a saving effected in the coal con- 
sumption of the engine, as steam cannot blow under 
the valve to the exhaust port and the engine will do 
the c ^ime work at shorter points of cut-off. 



BALANCED SLIDE VALVES. 

For a great many years the plain slide valve answered 
all the requirements for locomotive service, but with 
the enlargement of the locomotive and the increased 
steam pressures it was found almost impossible for one 
man to reverse an engine with such an enormous pressure 
on top of the large slide valve which modern locomo- 
tives require. The object of designers w r as, therefore, 
to produce a valve that would require as little power 
as possible to move it. To lessen this friction, what 
is known as the "Roller Valve" was first invented. It 
was a plain slide valve with rollers attached to each 
side of the valve. While this valve required less power 
to handle it, yet it failed to remove the cause of the 
great amount of friction between the valve and its seat, 
and therefore did not come into general use, although 
it is still in use upon some roads. But, when the balanced 
valve, sometimes called the equilibrium slide valve, was 
invented, the correct principle seems to have been fol- 
lowed, viz : The removal of the steam pressure from 
the back of the valve. These valves have been univer- 
sally adopted. The various forms of these valves that 
have been invented are too numerous to mention, but 
they are all constructed upon the same principle, that 
of removing the pressure off the valve. 

We have illustrated a few forms of these valves, 
varying all the way from very good to very bad. The 
best form of balance valve will be found to be the one 
which overcomes the greatest friction (within practical 

77 



78 



THE WALSCHAERT VALVE GEAR 



limits), the most simple in construction and positive 
in its operation and has the fewest parts which are 
liable to break or get out of working order. 

THE GOULD BALANCED SLIDE VALVES. 

Figures 44 to 49 serve to illustrate the construction 
and operation of the Gould balanced slide valves, of 
which there are two styles. 

These valves are the invention of Air. W. F. Gould 
of Des Moines, la. 




FIGURE 44. GOULD QUICK ACTION VALVE. 



The form known as the ''Quick action valve", Fig. 
44, deserves special attention. 

Heretofore it has been the generally accepted belief 
among practical men that it would be impossible to 
prevent the valve from lifting off its seat if all the 
pressure were removed from the top of the valve, but 
the action of the "quick action valve" appears to re- 
fute this theory. 



BALANCED SLIDE VALVES 79 

The principles of the Gould balanced valve are simi- 
lar to those of the piston valve. 

Either form of the Gould valve may be applied to 
the ordinary flat valve seat. 

Two methods of balancing are employed, one form 
of which, the "quick action valve" may be used with 
either a flat pressure plate, or a semi-circle balance plate, 
and promises to be an important rival to our best forms 
of balance valves. 

For the other form of valve the balance is obtained 
by means of a semi-circular balance plate fitted into the 
steam chest lengthwise. 

It is not bolted to the cover like most pressure plates, 
but rests on the valve seat. It has lugs that are closely 
fitted on the ends to prevent it from moving length- 
wise, while the pressure on its back serves to hold it to 
its seat. 

The top of the valve is also a semi-circle in form, 
slightly smaller than the plate and has balance strips 
set into it which bear against the plate in the usual man- 
ner. 

A small port at each end permits live steam to enter 
between the valve and the pressure plate, which is per- 
mitted to cover sufficient area to overcome the back 
pressure from the cylinder, thereby obtaining almost a 
perfect balance. 

In construction the two balance plates, (one for each 
valve) are first planed off on the edges, then the two 
are clamped together and bored out to their required 
size. 

The valves are finished in a similar way, first the two 
faces are planed off, then clamped together and turned 
off in a lathe, and made a little smaller than the pressure 
plate. 



80 THE WALSCHAERT VALVE GEAR 

When the valve requires facing, the same amount is 
taken off the bottom edges of the pressure plate also, 
thereby retaining their original positions, and the plates 
automatically adjust themselves to any inequality due 
to the wear of the valve. 

.Fig. 44 is a sectional view of the quick action valve, 
and. shows the relative positions of the small ports D, 
D ateitjiej end of the valve, to the ports leading to the 
cylinder. (Xot lettered.) 

The valve cover A is supported by four bolts to the 
steam chest cover, in such a manner as will permit of 
the cover A to be raised or lowered at will. H, H are 
ports in the base of the cover running longitudinally 
parallel to the steam ports. 

The ports D, D already referred to are longitudinal 
cavities in each end of the valve, and should be of the 
same length as ports H, H and nearly as long as the 
steam port that leads to the cylinder. 

E, E are packing bars placed on each side of the 
cavity D in the top of the valve in such a manner that 
the distance between them is of very little more area 
than the width of the steam port, for the purpose of 
holding the valve down when the steam port at the end 
of the valve is filled with steam. 

f In the operation of the valve as shown herein, when 
the valve is pulled back so as to open the steam port, 
it will be observed that the packing bar nearest that 
side will have also been pulled back so that the steam 
3t the top of the valve will pass over that top of the 
packing bar E into cavity H, thence through cavity D, 
into the steam port, thereby forming a double opening 
into: the cylinder. 

f. Another feature shown in Fjg. 44 is that, the valve 
on its return shows the port D in communication with 



BALANCED SLIDE VALVES 



81 



the steam port after cut-off has occurred, thereby show- 
ing the area between the packing bars E, E to be in com- 
munication with the steam in the steam port. This is 
done in order to balance the valve. 

It should be noted that the outside packing bar can be 
placed as near the outside end of the valve as desired, so 
as to take all, or nearly all of the pressure off of the valve. 




FIGURE 45. 



Another noteworthy feature connected with this -valve 
is, the relative position of the ports to each other when 
the engine is running at a high rate of speed, and a com- 
paratively short cut-off, or in other words, using the full 
amount of lead. 

In such cases there is more or less cushion, or back 
pressure in the cylinder but owing to the fact that port 
D will be in communication with the steam port, the bad 
effects of this back pressure are entirely obviated. 



82 THE WALSCHAERT VALVE GEAR 

When it becomes necessary to reverse the engine while 
running at a high rate of speed it will be observed, (by 
studying Fig. 44) that the valve will lift, and relieve the 
pressure in the cylinder, for the reason that the move- 
ment of the valve will be exactly opposite to the move- 
ment it had before the engine was reversed. 



© * © 


© * © 




Qu'Cm Actio* Vaivc 



FIGURE 46. 

In the plan view (Fig. 45) the relative position of the 
side bars and the end bars E to each other is clearly 
shown. 

The valve is also shown to have an open back, which 
prevents the exhaust steam from having any effect upon 



BALANCED SLIDE VALVES 



83 



the valve, but allows it to keep the bottom of the cover 
well lubricated. 

Fig. 46 shows a view of the bottom of the cover A. 
The ports H, are shown placed diagonally with the small 
bars C, in them. 

The reason that ports H are placed diagonally is to 
prevent ridges from becoming worn on the packing bars 
E as they move across ports H. 




FIGURE 47. GOULD BALANCE VALVE. 



GOULD BALANCED VALVE. 

Figs. 47 and 48 are sectional views of the Gould bal- 
ance slide valve, Fig. 47 being an end sectional view of 
the valve, valve cover and steam chest, and Fig. 48 is a 
vertical side sectional view of the same. 

Referring to Fig. 47 H, is a loose cover that fits over 
the top of the valve, and is prevented from having too 
much longitudinal movement by stops c, c. This move- 
ment should never exceed 1-16 of an inch over all. 



84 



THE WALSCHAERT VALVE GEAR 



The space occupied by the packing is designated by the 
dotted lines in the semi-circle, and this packing is en- 
closed in the pockets f, f, f. 

The letters k, k, represent a chipping strip upon the 
rear end of the valve, which may be faced off so that 
fie back end of the yoke d, mav fit it. 




FIGURE 48. 



The letters n, n, represent the sleeve, which is cast solid 
to each wing of the valve, and extends across the cavity 
o, in order to contain the valve stem b. 

The cavity o, is oblong in shape in order that the ver- 
tical movement of the valve may not bind upon the valve 
stem. 

The letters g, g, Fig. 47 designate two small holes 
drilled in the face of the valve for the purpose of es- 
tablishing communication between the port z, and the 
cavity x, shown in Fig. 48, 



BALANCED SLIDE VALVES 85 

Small ribs e, e, are cast upon the top of the valve cover 
h, in order to prevent the valve oil from running down 
the sides of the cover. 

These ribs e, e, also cause the oil to be distributed to 
the end of the cover, thereby effecting a more perfect 
lubrication of the valve and seat. 

Fig. 48 is a side sectional view of the valve, in which 
the packing rings are shown, held up by the spiral springs 
on one end of the valve, while the dotted lines on the 
opposite end of the valve designate the spring pockets. 

Two cavities x, x, Fig. 48 extend around the outside 
faces of each end of the valve, while the packing as 
shown is placed upon each side of these cavities x, x. 

The area of cavity x should always slightly exceed 
the area of the steam port z, in order that when port z, 
is filled with steam, and communication established with 
cavity x through hole g, (shown also in Fig. 47) the 
pressure in cavity x will at least equal the port pressure, 
and the valve will be held down on its seat. 

It will be observed that a practically perfect balance 
may thus be obtained, the degree of perfection depending 
upon the location of the packing rings, relative to the 
outside edge of the valve, and the giving of the proper 
area to cavity x. 

The check stubs y, y, Fig. 48, in the top of the steam 
chest cover are for the purpose of regulating the vertical 
movement of the valve cover h and preventing it from 
lifting too high from the valve. 

It will be observed that these stubs do not quite touch 
the valve cover, being adjusted to allow a slight move- 
ment in a vertical direction. 

Letters 1, 1, see Figs. 47 and 49, designate a web that 
holds the bottom of the wings of the valve firmly together 



86 



THE WALSCHAERT VALVE GEAR 



in one piece and prevents any leakage of steam into the 
exhaust, which might occur if the valve cover was raised 
from the seat. 

This valve is semi-circular in form and is constructed 
in the following manner. 



C 



o 



d 



c 



n a 



T. 



T 



U 



n a 



u 



H 



h,- ] -•;:- — 



JEL 



TL 



l^J 



TACC VICV/ 
eALANCC VALVC 



(J 



Kjz? 



FIGURE -19. 



JL 



a 



TJ 



o 



o 



o 



o 



As soon as the castings come from the sand their faces 
are planed and fastened together, and they are then 
placed in a lathe and turned to the proper size. 

Grooves for the packing, also cavities x are cut into 
their faces. The valve covers have their edges planed, 
and they are then fastened together and bored out to fit 
the valves, thereby making one for each side of the engine. 



BALANCED SLIDE VALVES 87 

The valves and their covers should fit iron to iron when 
they are cold, for the reason that when the cover becomes 
hot it expands a little more than the valve does, which 
leaves the valve free to move perfectly easy under it. 

When it becomes necessary to face the valve the same 
amount of iron should also be planed off of the bottom 
edge of the valve cover, thus causing each to assume their 
normal position relative to each other, and as cavity o 
in the valve through which the valve stem passes is made 
oblong vertically, it will readily be seen that facing the 
valve will not affect the valve stem in the least. 

When the exhaust is being planed out the tool should 
not be allowed to cut through line 1 shown in Fig. 49, 
which is a face view of the valve, and shows the form of 
the exhaust. 

The sizes of the ports will of course have to be gov- 
erned by the sized engine upon which the valve is to be 
used. 

The packing rings should have at least five-eighths of 
an inch face with a depth of one-half inch. 

The valve stem should be at least i]/ 2 inches in diam- 
eter, and the stops c, c, Fig. 47, should not be less than 
^8 of an inch in width. 

The valve cover should finish 1^4 inches in thickness, 
in order that there will be no danger of its ever becoming 
distorted, or out of shape. This thickness would also 
permit of it being bored out the second time to fit the 
valve. 

The depth of the cavities x should not be less than 
Y% of an inch and the diameter of the hole g, should be 
not less than 3-16 of an inch. 

The diameter of the bolts y should be not less than 
^4 of an inch. 



88 



THE WALSCHAERT VALVE GEAR 



The springs that are designed to hold the packing 
should be made of about No. 70 steel wire so that the 
pressure on them would be very light for the reason that 
if these springs are too stiff they will cause the packing 
to wear too fast or might hold the cover up from the 
valve when steam was not being- used. 



VACUUM RELIEF VALVE. 

This valve, R, Fig. 50, is designed to be placed in 
the steam chest to automatically supply clean air to the 
cylinders through the air valve when engine is running 
shut off, and thus furnishes a free supply of air from the 
outside instead of its being sucked in from the smoke box 
laden with hot gases and cinders which lap all oil from 
the valves and seats. 




FIGURE 50. VACUUM RELIEF VALVE. 



The pressure relief valve performs a very valuable 
function in preventing the dangerous accumulation of 
pressure in the steam chest and dry pipe and ofttimes 
breaking of same when engine is suddenly reversed. The 
valve is set to open at a pressure slightly above the max- 
imum boiler pressure, and will a!low T any excess of pres- 
sure to escape to the atmosphere, yet will maintain in 



BALANCED SLIDE VALVES 89 

the cylinders a uniform pressure of air within the limits 
of safety, when - running forward after reversing, and 
thus supply resistance to the pistons and overcome the 
momentum of the train, and perform the functions of an 
automatic air brake in assisting to stop the train. By 
using this valve an engine may be suddenly reversed 
while running at high speed without strain or damage 
to any portion of the machinery or boiler. 

This valve should be well designed and made from the 
best steam metal. Combined pressure and vacuum relief 
valves on low-pressure steam chest and single-pressure 
relief valves on low-pressure cylinder heads should be 
set at 45 per cent of the boiler pressure, and the high- 
pressure cylinder head relief valves set at 20 lbs. above 
boiler pressure. 

THE PISTON VALVE. 

Reference has already been made to the piston valve 
for locomotives and as there are many different varieties, 
of this type of valve, the discussion will be continued for 
a short space. 

The piston valve is an old affair in locomotive practice, 
having lain dormant for years. One of the early designs 
of these valves was that of Mr. Thomas S. Davis of 
Jersey City, in 1866. A difficulty which developed with 
his design and others at that time was the rapid wearing 
away of the valve cage at the port openings, due in part 
to the absence of bridge strips in the port openings, as 
ring-bearers for the piston. It was supposed also that the 
valve piston rings needed adjustment the same as those 
of the" steam cylinder piston. Occasionally this adjust- 
ment was faulty and, cramping the free motion of the 
valve, over-balanced all the advantage of the piston for 



90 THE WALSCHAERT VALVE GEAR 

the time being. The tallow then used for lubrication 
troubled the piston valve, as it did also the plain D valve. 
The cause which more than any other, however, led to the 
disuse of the piston valve after these early experiences 
was the introduction of the balance on the slide valve. 
This balance rendered the slide valve form acceptable at 
the then low pressure standard on engines. 

In the meantime the piston valve has gained a position 
at the head in steam vessels, small and large, naval and 
commercial, at all pressures the world over. It is used in 
fast steamers crossing the ocean, the entire distance being 
passed, in some instances, without lubrication. It is also 
used in the best and fastest electric engines running 
almost continuously. The piston valve has of late years 
been improved in form, eliminating the features which 
caused objections to the old form, and with the advent 
of high pressures it is fast coming into favor again. 

Owing to the fact that the piston valve is practically 
encased within the walls of the cylinder it permits of a 
greater port area, and occupies less space than the D 
slide valve does. 

It has been commonly supposed to be a perfectly bal- 
anced valve, but recent tests have proved that it is not 
as perfectly balanced as was generally supposed. 

It has been found that its perfection of balance depends 
largely upon the width of its rings, and the steam pres- 
sure, for the simple reason that so long as the steam 
exerts a pressure under the rings, thus holding them 
against the walls of the cylinder, there is thereby created 
an unbalanced friction the amount of which depends up- 
on the area of the rings, and the pressure of the steam 
under them. 

Of course a great deal depends upon the workmanship 



BALANCED SLIDE VALVES 91 

in the construction of the valve. The closer the rings 
are made to fit the grooves without binding, the better, 
but it is practically impossible to fit the packing rings 
perfectly steam tight without their sticking in the grooves, 
and the more the sides of the rings wear from service, the 
greater will be the steam pressure under the rings, and as 
a consequence the greater the friction. 

Owing to the usual forms of piston valves, they being 
generally made either of one long casting, or in two parts 
connected with a rod or tube, it is possible to locate the 
two faces near the ends of the cylinder, thus reducing the 
clearance considerable, as compared with the D valve. 

This lessening of the space to be filled with live steam 
between the piston and the valve face, for each stroke 
of piston, most certainly tends toward an increase in the 
efficiency of the engine, as the expansive force of the 
steam is in no way decreased, while the weight of steam 
to be exhausted at the completion of the stroke is con- 
siderably less. While the correct principle for reducing 
the clearance seems to be followed in placing these valve 
faces near the ends of the cylinder it should be remem- 
bered that while the distance between the valve and piston 
is lessened the clearance space extends clear around the 
valve and the claim of reduced clearance for these valves 
has frequently been overthrown by the Indicator. 

In the Vauclain Compound locomotive built by the 
Baldwin Co. the valve employed to distribute the steam 
to the cylinders is of the piston type, working in a cylin- 
drical steam-chest located in the saddle of the cylinder 
casting between the cylinders and the smoke-box, and 
as close to the cylinders as convenience will permit. 

As the steam-chest must have the necessary steam 
passages cast in it and dressed accurately to the required 



92 



THE WALSCHAERT VALVE GEAR 



sizes, the main passages in the cylinder casting leading 
thereto are cast wider than the finished ports. 

Fig. 51 shows the arrangement of the high and low 
pressure cylinders in relation to the valve. The steam- 
chest is bored out enough larger than the diameter of 
the valve to permit the use of a hard cast iron bushing 




FIGURE 51. 



SECTION OF CYLINDERS AND VALVE CHEST — 
VAUCLAIN COMPOUND ENGINE. 



(Fig. 52). This bushing is forced into the steam-chest 
under such pressure as to prevent the escape of steam 
from one steam passage to another except by the action 
of the valve. Thus an opportunity is given to machine 
accurately all the various ports, so that the admission of 
steam is uniform under all conditions of service. 

The valve, which is of the piston type, double and 
hollow, as shown in Fig. 53, controls the steam admission 
and exhaust of both cylinders. The exhaust steam from 



BALANCED SLIDE VALVES 



93 



the high-pressure cylinder becomes the supply steam for 
the low-pressure cylinder. As the supply steam for the 
high-pressure cylinder enters the steam-chest at both ends, 



.^ v> 




FIGURE 52. BUSHING FOR VAUCLAIN PISTON VALVE. 

the valve is in perfect balance, except the slight variation 
caused by the area of the valve-stem at the back end. This 
variation is an advantage in case the valve or its connec- 
tion to the valve-rod should be broken, as it holds them 




FIGURE 53. 



PISTON VALVE USED ON VAUCLAIN COMPOUND 
LOCOMOTIVE. 



together. Cases are reported where compound locomo- 
tives of this system have hauled passenger trains long 
distances with broken valve-stems and broken valves, the 



94 THE WALSCHAERT VALVE GEAR 

parts being kept in their proper relation while running by 
the compression clue to the variation mentioned To avoid 
the possibility of breaking, it is the present practice to 
pass the valve-stem through the valve and secure it by a 
nut on the front end. 

Cast iron packing rings are fitted to the valve and con- 
stitute the edges of the valve. They are prevented from 
entering the steam-ports when the valve is in motion by 
the narrow bridge across the steam-ports of the bushing, 
as shown in Fig. 52. The operation of the valve is clearly 
shown in Fig. 51, the direction of the steam being in- 
dicated by arrows. 

In setting these piston valves, only the high-pressure 
ports are to be considered. Both heads of the steam 
chest are removed, and with a tram, from some point on 
the body of the cylinder to the valve stem, the line and 
line positions of the valve in both front and back motion, 
are laid off and indicated by a prick punch mark on the 
valve stem. Using the same tram, the position of the 
valve at different parts of the stroke can be ascertained, 
and the opening of the ports noted by the distance from 
the point of the tram to the prick punch mark. The re- 
lation of the low pressure ports to the valve must be as- 
certained by measurement, the same as the exhaust ports 
in ordinary slide valves. 

THE AMERICAN BALANCE VALVE. 

This form of balance can be applied to almost every 
form of slide valve. 

The American balance valve Fig. 54, has been adopted 
by a great many of the principal railroads in this country, 
consequently we give details of its construction, believing 
it will be interesting to a large number of our readers. 



BALANCED SLIDE VALVES 



95 



It has also attracted the attention of foreign builders and 
is now in use upon many locomotives in other countries. 
It is claimed many thousands of these valves are in use, 
being used by no different railroads in this country and 




FIGURE 54. 

many foreign roads ; also on marine and stationary en- 
gines. One of our illustrations shows its application to an 
Allen ported valve. The claims made for this form of 
balance are : 



i. Self supporting — when not under steam. 

2. Supported by steam — when under steam. 

3. Automatic adjustment — with or without steam. 

4. Absolute steam joints — no waste from leakage at 
any time. 

5. Positive action — impossible for ring to stick. 

6. A T 6> lateral wear — ring moves as part of the cone 
itself. 

7. Permanency of cone — cones retain original dia. 
and taper. 

8. Standard sizes — rings interchangeable, old or new. 

9. Stock — carried in stock for new work or repairs. 
10. Lathe work — stock from the lathe is economy. 



96 



THE WALSCHAERT VALVE GEAR 



11. Greater area of balance — equaled by no other de- 
sign. 

12. Simplicity — always most desirable in machinery. 

It is claimed by the makers of this valve, (The Ameri- 
can Balance Valve Co. of Jersey Shore, Pa.) that, 
first of all it furnishes an absolutely steam tight joint, 
not only when newly fitted, but all the time. 




FIGURE 55. RINGS AND CONES— AMERICAN BALANCE VALVE. 



Second, greater area of balance, the valve being 
balanced in what is presumably its heaviest position, and 
with the steam pressure acting upon the conference of 
the taper rings, (See Fig. 55) it will be observed that 
for the valve to lift off its seat, it is necessary to force the 
cone up into this taper ring, and since the ring is held 
by the steam pressure from opening, the valve cannot 
lift without first overcoming the entire friction of the 
beveled face, besides opening the ring against the pressure 
in the steam chest. 

It will therefore be seen that, whether the chest pres- 



BALANCED SLIDE VALVES 97 

sure be heavy or light the valve is always retained upon 
its seat. 

It might at first glance appear to be a natural conclu- 
sion that this taper of rings and cones would crowd the 
valve down on its seat unnecessarily hard, and no doubt 
it would have that tendency if the degree of taper was 
made great enough, say 45 degrees for instance, in which 
case the action of the steam chest pressure upon the cir- 
cumference of the ring would of course wedge it in be- 
tween the cone and the chest cover and thus exert an 
enormous pressure upon the valve. 

Experience has however demonstrated that there is a 
correct degree of taper, which varies all the way from 9 
to 24 degrees, to be given to the rings and cones, depend- 
ing upon the style of valve, whether it be single "disc," 
double "disc," single cone, etc., and the claim is made that 
rings have run 190,000 miles with but 1/32 inch wear off 
their faces. 

It is also claimed in favor of this system of balance, 
that it is positively automatic, in adjustment, also self 
supporting, with no delicate parts, and therefore not 
easily broken having, no springs. 

The only repairs necessary on the American balance is 
to put in a new ring when the old one has worn out from 
the top downward. 

The new rings are one inch in depth, and they can 
easily wear V% inch, and still adjust themselves. 

Assuming that the rings are made of the proper quality 
of metal, and that they receive the proper care in service, 
the time required to wear }i inch from the face, would be 
from four to eight years of continuous service. 

It will thus be seen that the cost of repairs is very 
light, and another great advantage is, that when an old 



98 



THE WALSCHAERT VALVE GEAR 



ring is replaced by a new one there is absolutely no 
change in the balance. 

This is explained by the fact that since the steam pres- 
sure on the circumference of the ring holds it firmly 
against the beveled face of the disc or cone, while in 
operation, under steam (its own tension holding it when 
not under steam), there is absolutely no lateral wear on 
either the ring, or the disc, consequently a new ring fits 
an old disc. 




FIGURE 56. T RING— AMERICAN BALANCE VALVE. 



The rings are made from standard gauges which are 
used on the lathe in place of a caliper, or rule, and as the 
rings are all lathe work the time required for fastening on 
the L-shaped piece for covering the cut of the ring is 
very short, not more than twenty minutes hand work. 

In turning up the rings, they are made )A inch smaller 
in diameter than their working diameters. They are then 
cut, and expanded over the cone which gives them a ten- 
sion that makes them self supporting when not under 
steam. 



BALANCED SLIDE VALVES 99 

The pressure of the steam on the circumference of the 
ring supports it when in operation. 

The latest improvement in this form of balance is the 
T ring (Fig. 56) ; the flanges on the top of the ring give 
an extra width for wearing surface, which prolongs the 
life of the ring. The top face of the ring is provided with 
a small groove for oil. The L-shaped joint plate forms 
joints both on the beveled face and at the top of the ring. 
The "outside rim" or flange extending outside the taper 
ring is to prevent pieces of the ring from falling in the 
path of the valve in the event of accident to the ring. 



SINGLE DISC BALANCED VALVE. 

Always use the single balance where chest room will 
permit it, as one ring and disc is simpler than two. 

For length of steam chest for single balance add the 
extreme travel of the valve to the outside diameter of 
disc, and to this sum add not less than )/ 2 inch for clear- 
ance- — ^4 inch at each end of chest. If a little more clear- 
ance is desired the rims of disc may be cut }£ inch — just 
flattened on two sides in line of valve travel. But in no 
case are they to be cut beyond their inside diameter. 

If sufficient clearance cannot be obtained by cutting the 
rims Y§ inch each side in line of valve travel, then double 
balance must be used. 



DOUBLE DISC BALANCED VALVE. 

When the steam chest is too short to leave clearance 
for the outside diameter of the disc, or cone of single 
balance at extreme travel of valve, it then becomes neces- 
sary to use double balance. 



100 THE WALSCHAERT VALVE GEAR 

If the yoke fit (or box) of the valve is large enough 
two cones are cast on the valve, but in case the yoke fit 
is not large enough to cast cones on, then two discs are 
used. 

If the distance across the two discs when they are side 
by side on top of the valve is greater than the width of 
the steam chest, the rims on each disc may be cut J /$ inch 
at the center of the valve, thus drawing the discs x 4 mc h 
closer together, and if more clearance is still required the 
rims may also be cut J /s inch and the ends of the valve, 
thus giving y inch more, making a total of y 2 inch. 

But in no case should the rims be cut more than y& 
inch or to their inside diameter. 

If discs thus cut will not clear the sides of the steam 
chest, it will be necessary to use a smaller balance. 

"DISC" BEARING ON CONE. 

In all cases where possible the height adjustment should 
be made by lowering the cover of the steam chest, or 
bearing plate, but when this cannot be done, the discs 
may be raised. 

When it becomes necessary to raise the disc on the 
valve, longer bolts should be used, and the liners placed 
between the disc and the valve must be true, and large 
enough to give a solid bearing for the disc on the valve. 

If it is found necessary to raise the disc to clear the 
top of the valve, the same rules must be observed. 

The bolts that hold the disc to the valve should be 
steam tight on threads, also steam tight under the heads, 
a copper washer being used under the heads, thus form- 
ing a bolt lock. 

The interior of each disc or cone is relieved to the 
exhaust cavity of the valve. 



BALANCED SLIDE VALVES 101 

In "cone" balance, relief holes are drilled through the 
top of the valve, but in "disc" balance these relief holes 
(yi inch in diameter) pass through the bolts, one hole 
through each bolt 

SINGLE "CONE" BALANCED VALVE 

This style of valve must be cast flangeless if a valve 
yoke extending all around the valve (as in locomotives) 
is used, but need not be flangeless when made for center 
rod to drive the valve (as in stationary engines). In case 
of the locomotive yoke we recommend the yoke to be 
carried on the steam chest at the ends of the valve. Where 
old chests have rubbing strips wide enough they can be 
planed on top and the yoke allowed to ride on them, and 
in new work this can be done cheaper than to put on a 
front carrying horn and is more efficient than to support 
the yoke on the valve stem packing the valve itself. A 
valve need not be flangeless to thus support the yoke, it 
can be carried with any valve, and it insures the free up- 
ward movement of the valve at all times, w T hich is very 
essential in obtaining the best results. 

OUTSIDE RIMS. 

The outside rim on disc or cone is merely a safeguard 
to the ring in case of accident — it performs no other 
duty. The required inside diameter of this rim must 
allow the ring to be expanded on the cone until the top 
face of the ring is flush with top of cone and still clear 
the y% inch joint plate on the outside of ring. In single 
balance the rims may be cut J /$ inch front and back, giv- 
ing 34 inch more clearance, when the disc runs too close 
to steam chest at full travel of valve. 



102 THE WALSCHAERT VALVE GEAR 

In double balance the rim of each disc may be cut Y /% 
inch so as to draw the discs Y\ inch closer together at 
center of valve, and if more clearance at sides of chest is 
required the rims of each disc may be cut at ends of valve 
also. The distance across the two discs can thus be 
shortened y 2 inch. 

In no case shall the rim be cut more than % inch. 
The two cones where they come together at center of 
valve in double balance must not be less than ^4 inch 
apart at the bottom. 

If discs thus cut will not clear the steam chest, then 
smaller balance must be used. 



HEIGHT ADJUSTMENT. 

When the valve is in position and the chest cover has 
been screwed down there must be j4> inch between the 
face of the bearing plate (sometimes called balance plate) 
and the top of disc or cone. 

The rings are bored for this position and in this posi- 
tion have their proper tension. This allows the valve to 
lift off its seat J /s inch, which it will do as soon as steam 
is shut off while the engine is in motion, provided it is 
not held down by the valve yoke. 

The valve yoke must not interfere with this upward 
movement of the valve. 

Rings are all bored smaller than the diameter at which 
they are to work; therefore when a ring is set on its 
proper cone it will stand higher than its working position. 

The face of bearing plate must not be closer than ]/% 
inch to top of cone after chest cover has been screwed 
down. In placing the cover in this position the ring is 
expanded over the cone until its inside diameter at bottom 
is the proper balancing diameter. 



BALANCED SLIDE VALVES 103 

Owing to the natural elasticity of the ring and its ex- 
pansion over the cone, a tension is placed on the ring, the 
action of which is (the same as the steam pressure) to 
close the ring on the cone, which necessarily moves up- 
wards. 

The ring is therefore self-supporting and self-adjust- 
ing. All rings are interchangeable on discs and cones 
of respective sizes whether standard or special. 



BALANCES. 

American balances are known under the following 
heads, one valve being balanced in each case : 

Single "disc" balance, i. e., one ring and one disc. 

Double "disc" balance, i. e., two rings and two discs. 

Single "cone" balance, i. e., one ring with cone cast on 
valve. 

Double "cone" balance, i. e., two rings with two cones 
cast on valve. 

CYLINDER RELIEF. 

The valve shall always be free to lift }i inch off its 
seat, to allow the free passage of air from one end of 
the cylinder to the other, between valve and valve seat, 
when engine is running without steam. The tops of all 
American balance discs, or cones, show a polish, giving 
positive evidence of their contact with the bearing plate 
or cover, and that they therefore do float. 

The explanation is : At the first stroke of the piston, 
after engine has been shut off, air is compressed in one 
end of the cylinder while the valve is traveling a distance 
equal to its outside lap; at an early stage of this com- 
pression the valve is thrown off its seat and the escaping 



104 THE WALSCHAERT VALVE GEAR 

air rushes under the valve into the opposite end of the 
cylinder to relieve the suction which is taking place in 
that end; this operation is repeated so rapidly that the 
valve is kept floating until a slow speed has been reached. 
Sufficient air is always drawn in, through the (lift 
valve) cylinder cocks, and exhausted through the exhaust 
port, to keep the current of air in the direction of the 
stack, but not enough to "fan the fire." This affords the 
most perfect cylinder relief and vacuum valves in steam 
chest are not a necessity. 



FORMULAE OF BALANCE USED (AMERICAN BALANCE VALVE ) . 

Area of balance for plain valves. 

Area of one steam port, two bridges, and the exhaust 
port, plus 8% if for single balance, and plus 15% if 
double balance. 

Example for single balance. 

Steam port, 1^" plus bridge 1" plus exhaust port 2V2" 
plus bridge 1" equals 5%" X 16" equals 92 sq. in. 
8% of 92 equals 7.36. 
92 plus 7.36 equals 99.36 sq. in. equals area. 

Example for double balance. 

Steam port i%" plus bridge 1" plus exhaust port 2y 2 " 
plus bridge 1" equals 5^4" X 16" equals 92 sq. in. 

15% of 92 equals 13.80. 

92 plus 13.80 equals 105.8 sq. in. equals area. 

105.8 divided by 2 equals 52.9 equals area of each ring. 

The nearest diameter for 52.9 equals 8 T 4 in., which is 
the diameter for each ring. 

For Allen ported valves, use the same formulae as 
above, then from the area derived subtract the area of 
one side of the Allen port. 



BALANCED SLIDE VALVES 105 

Example. 

iy 2 plus \}i plus 3 equals J 1 /^ in. X 17 equals 123.25 

sq. in. plus 15% equals 141.73 sq. in. equals area. 
Allen port equals y 2 X 17 equals 8j4 sq. in., then, 
141.73 minus 8.5 equals 133.23 sq. in., which divided 

by 2 equals 66.61 sq. in. equals area of each ring. 



THE BARNES BALANCED VALVE. 

The following description and illustration of the Barnes 
balanced valve is taken from "Locomotive Engineering" : 
A balanced valve having some points with a strong flavor 
of originality is that designed and patented by Superin- 
tendent of Motive Power Barnes, of the Wabash Rail- 
road, and illustrated in Fig. 57. 




:£ rt-i -* 

bU Ud I 1 l!*J j JLJbfeJ 

2jxomoiivt Englnttrlng 

Cast Iron. 4 Pieces Cast Iron. 4 Pieces 

FIGURE 57. BARNES BALANCED VALVE — LONGITUDINAL 
SECTION. 



The full size part of a longitudinal section will per- 
haps give a clearer idea of the balance part of the device 
than will a first reference to details. 

This view shows a cast iron frame surrounding the 
valve, with a recess equal to the width and depth of the 
balance strips on its inner face. 

106 



BARNES BALANCED VALVE 107 

There are four balance strips ^sxi^ in. carried in 
position by the frame, which latter is 1^x2 j4 in. in the 
overall dimensions of its cross section. 

Both the frame and the strips are cored for lightness. 

The combination is held up to the balance plate by 
four helical springs made of German silver wire 0.125 
in. in diameter. It is seen that the balance strips have a 
very deep bearing between that valve and frame, and 
since the strips are carried by the frame, there must be 
a constant depth of support to them on the outside face, 
no matter how much wear takes place, nor what the lift 
of the springs. This condition of things tends to reduce 
the liability of cocked or broken strips as has been found 
in service. The springs placed at the ends of the frame 
would seem to exert a more equable pressure on all the 
strips than is possible with a long spring under each 
individual strip, for the reason that it is a delicate under- 
taking to attempt to make four flat springs of the same 
degree of elasticity. 

On these grounds it is not unreasonable to expect a 
continuance of the good results so far shown by this style 
of balance. The dimensions shown are for a ten wheeler. 



the Mcdonald valve. 

The points of advantage claimed for this valve are as 
follows : First, that the pet cock on top of the steam 
chest cover is always open to the atmosphere, so that 
should the joint leak, the engineer will be able to see the 
steam escaping through the pet cock, which is sure evi- 
dence that the valve requires attention. 




figure 58. Mcdonald valve. 



Second, he can then close the pet cock and the valve 
will operate on the same principle as a simple D valve. 

Third, the U shaped packing strips maintain a satis- 
factory and tight joint and the flat steel spring beneath 
the valve is of the simplest form. This valve has recently 
been introduced into this country. Mr. McDonald, the 
inventor, is a mechanical engineer at Yokohama, Japan, 
and has had these valves in service some two or three 
years, and it is claimed they are giving excellent results. 

The McDonald valve in shown in vertical section in 

Fig. 5§- 

108 



THE BRIGGS BALANCED VALVE. 

The following illustrations (Figures 59 to 63) and 
description of this valve is taken from Locomotive En- 
gineering: 

The inventor, Mr. R. H. Briggs, Jr., of Amory, Miss.^ 
describes this valve as follows : 



Balance Plate 



FIGURE 60. 
Balance Plate 




Inside ring broken here 
FIGURE 61. 



Locomotive 'Engineering 

FIGURE 63. 



"You can readily see that it will require very little ex- 
planation as to the operation of this improved balance. 
This balance consists of four parts — cone E, two packing 
rings B and joint ring A. The packing rings are cut as 
shown in Fig. 62. To break the joints these rings are 

109 



110 THE WALSCHAERT VALVE GEAR 

pinned together. To prevent the cuts working around, 
they are also ground on cone E, to prevent any leak at 
bottom of packing ring. They have a ball joint on top 
with joint ring A perfectly ground to them. Joint ring 
A is a nice, neat fit on cone E. Now you can very 
readily see that it is impossible for this valve to blow, as 
the greater the steam pressure on the outside of packing 
rings B the tighter ring A will be on the balance plate. 
I give these rings only 1-32" compression. Another ad- 
vantage that I claim for this valve is that it balances to 
outside diameter of outside packing rings B." 



THE MARGO VALVE. 

The Margo balanced valve was one of the first forms 
of balanced valves. It had two small discs and small 
packing* rings (similar to air pump packing rings) ; the 
steam pressure holding the disc up against the pressure 
plate. Much trouble was experienced with this form of 
valve, owing to a gumming up of its parts wdiich would 
cause the disc to stick. Very few of these valves are now 
in use. 



Ill 



POWER REQUIRED TO' MOVE A VALVE. 

To determine the power required to move a valve 
multiply the area of the valve face by the steam pressure 
upon it less y$ allowed for back pressure from the steam 
port and exhaust port. The friction between two smooth 
surfaces well lubricated varies from i-io to 1-14 of the 
pressure (the weight of the valve being so slight it is 
seldom considered. Friction is the resistance which two 
contracting surfaces have to being moved one over the 
other and is of three kinds : Sliding, rotation, and 
liquid). For example: If a valve face measures 10x20 
with 120 pounds' pressure proceed as follows: 

10X20=200X120= 24,000 

8,000 less one third, 



Divided by the friction, 10 16,000 1,600 lbs. power 

required. 



112 



THE ALFREE VALVE. 

In the Alfree system of steam distribution as applied 
to locomotives by the Locomotive Appliance Co. of Chi- 
cago, a somewhat new departure from standard practice 
is made. 

This consists in what is termed a compression con- 
trolling valve, in addition to the main valve which con- 
trols admission, cut-off, and release. According to the 
claims of the manufacturers "this system not only em- 
bodies principles that are entirely new but utilizes old 
and well known principles in the use of steam not here- 
tofore suitable for locomotive uses because of the com- 
plication of the mechanical means necessary for their use, 
together with the peculiar and severe conditions under 
which they must operate. 

"The mechanical means for producing these results 
are extremely simple; the few special features being 
contained within the valve chambers of the cylinders. 
All that is necessary for an application of the system to 
a locomotive is to apply our cylinders in precisely the 
same manner as standard cylinders connecting the valve 
stems to the standard rockers and making the usual ad- 
justments. It involves substantially a change of cylin- 
. ders only. Any of the standard valve gears, Stephenson, 
Walschaert or any other may be used. 

"The following is a brief analysis of the means 
through which these results are attained: 

"i. Reduced Heat Losses. Our cylinders are de- 
signed with short ports and the exhaust passages carry- 
ing cold steam are separated and insulated from the live 

113 



114 



THE WALSCHAERT VALVE GEAR 




THE ALFREE VALVE 115 

steam passages ; consequently heat losses from radiation 
and condensation are greatly reduced. 

"2. Less Steam Used for a Given Cut-off. The waste 
spaces in the cylinders are reduced to the minimum. In 
common practice this amounts to at least io»% of the 
piston displacement, while our cylinders have not more 
than 2.5%. To illustrate, for a 7-inch cut-off in a 30-inch 
stroke engine we, in effect, draw upon the boiler for 7^ 
inches of steam, while for a like cut-off in a standard en- 
gine it will require an average draft on the boiler of 10 
inches of steam. 

"3. Higher Ratio of Expansion. B'ecause of the mini- 
mum waste spaces in the cylinders and of the ability to 
hold the steam in the cylinders longer before exhausting 
it, we get a higher ratio of expansion — that is, more work 
— out of the steam admitted to the cylinders. 

"4. Perfect Exhaust. Having an increased exhaust 
area of about 50%, this system produces a quick, 
extraordinarily free, and large opening of exhaust, dis- 
charging the exhaust steam perfectly and quickly. This 
greatly reduces back pressure, or negative work, in the 
cylinders, and, due to the sudden release, a better fire is 
maintained even with an enlarged exhaust nozzle. 

"5. Reduced Negative Work. In the return or ex- 
haust stroke of the piston the exhaust is not closed until 
very late in the stroke ; but when the proper point is 
reached, just enough exhaust steam is entrapped in the 
cylinders and small clearance spaces to produce sufficient 
compression to answer the mechanical needs of cushion- 
ing. In the standard locomotive the exhaust is closed 
comparatively early in the stroke and negative work 
commences correspondingly early. As the compression 
begins early in the standard engine, a large amount of 
clearance space must necessarily be provided to prevent 



116 THE WALSCHAERT VALVE GEAR 

compression running too high ; and a correspondingly 
large amount of negative work must be done to compress 
the larger volume. Therefore, the negative work of com- 
pression in our engines is reduced enormously and a cor- 
responding amount of available positive work is added. 

"6. Increased Turning Effort, It is found in locomo- 
tives where the power is applied to the drivers through 
rotative rather than reciprocating motion that such loco- 
motives pull, without slipping of the drivers, considerably 
greater tonnage than the standard locomotive of the same 
weight. The reason for this is that the power is applied 
steadily in one case and intermittingly in the other. In 
the reciprocating engine, if the release is early and an 
unnecessary resistance set up on the opposite side of the 
piston, more steam must be applied in the center of the 
stroke to make up for losses at each end. Consequently, 
the power is applied to the drivers intermittingly, pro- 
ducing a jerky effect, and the limit of adhesion of the 
drivers is reached long before the real power of the en- 
gine can be used. But in our system by holding onto the 
steam longer at one end and by removing the resistance 
at the other end of the stroke, higher average pressure 
will result and the power distributed more evenly through 
the stroke ; thus imparting to the drivers a steadier or 
more even rotative effect, increasing the available power 
of the engine and greatly decreasing tendency of 
slipping.'' 

"It is a well established fact in standard locomotive 
practice, that a single valve either of the piston or flat 
type, will perform three out of its four functions per- 
fectly, viz. : admission cut-off, and release, but the fourth, 
known as closure, or the compression event, is wrong. 
If the valve is provided with a sufficient amount of 
exhaust lap, to obtain an economic expansion through 



THE ALFREE VALVE 117 

delaying the release, the exhaust closure becomes exces- 
sively early,, and an enormous clearance space must be 
provided equal to fully 15% of the piston displacement. 
This entails such a loss that a compromise is generally 
effected by reducing the exhaust lap, making the release 
earlier but delaying the closure to a point where not to 
exceed 10% of clearance space need be provided This 
requires a valve having its exhaust edges about equal 
to the exhaust edges of the ports,, generally designated 
as line and line, or if the valve is cut a little shorter, 
giving say about one-eighth exhaust clearance, the clear- 
ance or waste spaces may be reduced to about 8% of the 
piston displacement Any further reduction of exhaust 
lap would result in a greater loss through an early re- 
lease than would be gained through a reduction of clear- 
ance. 

"In the Alfree System a single valve correctly controls 
admission, cut-off and release the same as in the standard 
engine, except that a sufficient amount of exhaust lap 
is used to carry the steam to a point that will give a 
greater expansion. Then to avoid an early closure, a 
small piston valve, called the Compression Controlling 
Valve, is introduced through a section of the ports be- 
neath and to one side of the main valve, and has only 
the function of controlling the compression and providing 
greater freedom for the escape of exhaust steam. While 
the two valves release at the same instant, the compres- 
sion valve in closing falls about one and one-fourth inches 
behind the main valve. This allows the exhaust steam 
that would otherwise be in compression, to escape until 
the piston reaches about 90% of its stroke (at *4 cut-off) 
or within 2^/2 or 3 inches of the end of its stroke. The 
clearance having been reduced to 2^4% of the piston 



118 



THE WALSCHAERT VALVE GEAR 



displacement, a sufficient amount of compression takes 
place to perfectly cushion the reciprocating parts. 

"It will be seen that through these simple means we 
are enabled to greatly reduce the inherent losses, increase 




FIGURE 65. ALFREE CYLINDER, WITH STEAM CHEST COVER, 
AND VALVES REMOVED. 

the mean effective pressure, increase the effective exhaust 
area, and increase the turning effort on the drivers. The 
results as found by actual test are 5% to 8% more ton- 
nage, with 8% to 10% less fuel and water, higher speeds, 



THE ALFREE VALVE 



119 



fewer engine failures, and reduced running repairs. 
These are positive and practical facts which will not only 
be found true by critical examination of the system, but 
will be better proven by actual use/' 

Fig 65 shows the Cylinder with Steam Chest Cover 
and Valves removed. As will be seen, the Cylinder and 
Valve Chamber or Steam Chest are one casting ; the 
ports are short and practically straight with the Com- 
pression Valves passing through their longest section. 
The admission is from the inside, which brings the live 




FIGURE 66. STEAM CHEST COVER. 



steam in contact with a considerable portion of the Cyl- 
inder walls, while the exhaust is at the ends and is most 
effectually insulated from the live steam, thus eliminating 
one of the greatest sources of heat loss. Double walls 
are used around all live steam passages wherever practi- 
cable with the object of making the insulation as perfect 
as possible. This design produces an exceptionally 
strong cylinder well adapted to resisting shocks which 
would often destroy Cylinders of the ordinary design. 



120 THE WALSCHAERT VALVE GEAR 

The Combined Steam Chest Cover and Pressure Plate, 
as shown by Fig. 66, has a by-pass chamber connecting 
with each end, thus permitting a portion of the exhaust 
from one end to flow through the exhaust passage at the 
opposite end, which greatly aids in preventing the induc- 
tion of cinders into the cylinder when drifting. Between 
this by-pass chamber and the face of the cover a dead 
air space is provided, insulating the live steam from the 
exhaust steam, while the exhaust steam, passing through 
the by-pass, insulates the dead air chamber from the 
atmosphere, which is somewhat further shut off by the 
usual cylinder casing. The cover also serves as a Pres- 
sure Plate for the Main Valve. 



GENERAL ARRANGEMENT OF PARTS. 

The general arrangement of Valves, Valve Chambers, 
Steam Chest Covers, etc., is shown in Figs. 67 and 63. 

The Steam Chest or Main Valve Chamber is on an 
angle of 15 with the horizontal and placed close to the 
cylinder bore. The ports are short and practically 




%JS — 



FIGURE 67. THE ALFREE SYSTEM. 

straight so that their surfaces may be scraped clean and 
smooth. The Compression Controlling Valve Chamber 
passes through the longest section of the ports, and is 
bushed in the usual way to provide for repairs. The 
Steam Chest Cover forms the top side of the Main Valve 
Chamber and provides a by-pass connection between the 
exhaust passages which equalizes exhaust pressures. 

121 



122 



THE WALSCHAERT VALVE GEAR 



The Main Steam Valve is of rectilinear form rigidly 
constructed and designed so that the wear is uniform 
regardless of the travel. It is balanced for all speeds and 
under all pressures, running or drifting, and with its 
wearing surfaces nearly doubled by special riding shoes, 
the wear on the Valve and Valve Seat is very slight. 




TRANSVERSE SECTION. 
FIGURE 68. THE ALFREE SYSTEM. 



The Compression Controlling Valve is a piston valve 
of the usual design except that it is very light and pro- 
vided with wide snap rings to overlap the ports and for 
protection against wear. It takes its motion from the 
Main Valve by means of an arm connection of rigid con- 
struction. 



GENERAL ARRANGEMENT OF PARTS 



123 



The admission of steam to the cylinders and the cut-off 
is controlled by the Alain Steam Valve. Steam is ad- 
mitted along the entire lower edge and up one side, pro- 
viding an unusually large port area for admission. Ex- 




figure 69. 



haust also is controlled by the Alain Steam Valve, but 
to this is added the exhaust of the Compression Con- 
trolling Valve which releases simultaneously with the 
Alain Valve. 



100 



104 



96 



FIGURE 70. 



Closure or Compression is controlled entirely by the 
Compression Controlling Valve, which delays the final 
closure of the exhaust until the piston has completed 
90% of its stroke at the short cut-offs, thereby reducing 



124 THE WALSCHAERT VALVE GEAR 

the volume of the exhaust steam in Compression from 
about 10 inches in the usual practice to 2% inches in this 
system 

Fig. 69 is a diagram furnished by the Locomotive 
Appliance Co. of Chicago, which that company claims 
shows the effective turning effort of the piston to be ap- 
plied throughout the greater part of a revolution of the 
drivers. 




figure 71. 

Fig. 70 is an enlarged sample of the same card. Fig. 
71 is another sample of an indicator diagram taken from 
a locomotive equipped with the Alfree cylinders and 
valves. 

These diagrams certainly show great efficiency in the 
use of the steam. 



VALVE DIAGRAMS. 



The action of the valve, and the relative positions of 
the crank pin, and eccentric during the stroke, may be 
graphically illustrated by means of valve diagrams. 

There are several different kinds of diagrams employed 
for this purpose. 

♦ 90° 




f%o { 



FIGURE 72. 

In this connection the Reuleax and Zeuner diagrams 
will be used, and first we will make use of a simple dia- 
gram in order to bring the subject clearly before the 
mind of the student. 

Referring to Fig. 72, the inner circle represents the 
path described by the high point of the eccentric, and the 
large circle that of the crank pin. The radius C2 of the 
small circle represents the throw of the eccentric, and the 

125 



126 



THE WALSCHAERT VALVE GEAR 



distance CL is the lap of the valve plus the lead. The 
point of intersection of the vertical line, Li, with the ec- 
centric circle locates the position of the highest point of 
the eccentric, and the line CB, drawn from the center of 







FIGURE 73. 



the crank shaft through this point, indicates the angular 
advance, which in this case is 30 represented by the 
angle ABC. The figures 1, 2, 3, 4, 5 indicate the position 
of the high point of the eccentric at the moment of each 
function of the valve. 

Fig. 73 shows the total movement of the valve, regard- 
less of lap and lead. First draw line Ci to represent the 



VALVE DIAGRAMS 127 

center line of the engine. Next draw line C4 perpendicu- 
lar to the line of centers, with C as the center of the 
crank shaft. The radius of the semi-circle D, I, 2, 3, 4, 
5, 6 equals the radius of eccentricity. Line CD represents 
the position of the crank when the valve is at mid-travel 
or in its central position, D being the location of the 
crank pin. 

Again referring to Fig. 73, draw line CA in such a po- 
sition that the angle ABC will equal the angular advance 
of the eccentric, which we will assume in this case to 
be 30°. 

This will bring the high point of the eccentric at B, 
while the crank pin, as before stated, is at D. Next, 
using line CA as the diameter, draw a circle about it, 
called the valve circle. Now, suppose the crank to be 
turning in the direction of the arrows. At position D 
the crank line is just about to cut into the valve circle, 
the valve being central. When the crank gets to position 
1 the valve has moved the distance CE. When the crank 
is at 2 the valve has moved the distance CM, and w T hen 
the crank arrives at 3 the valve has moved to the limit 
of its travel from its central position and it now begins 
the return movement. The motion of the valve is com- 
paratively slow at this point for the reason that the high 
point of the eccentric is now passing the center at 7. The 
distance the valve has moved backward while the crank 
has moved from 3 to 4 is the distance BF, while FC 
represents its distance from the central position, and GC 
the same when the crank is at 5. When the crank arrives 
at 6 and its line has left the valve circle, the valve is 
again central. Fig. 73 merely shows the movement of 
the valve through one-half of its travel without giving 
any details regarding port openings, cut-off, etc. 



128 



THE WALSCHAERT VALVE GEAR 



In Fig. 74 the influence of outside lap is delineated. 
According to the dimensions of the valve under consider- 
ation the outside lap is one inch. The diagram is drawn 
precisely as in Fig. 73, and in addition strike an arc 
representing the outside lap, using C as the center with 




Vafve Aave/ - £/»'** 



Aacft 






FIGURE 74. 



a radius equal to the outside lap. As before, the crank is 
at D and the valve central. When the crank has moved 
to E and its line cuts the intersection of the outside lap 
and valve circles, the valve has moved the distance CH, 
just equal to the outside lap, and the port begins to un- 



VALVE DIAGRAMS 



129 



cover at this point. Then by the time the crank gets to 
the center, I, the port is open the distance LO, which is 
the lead, in this case }& inch. 

The position of the crank when cut-off takes place is 
ascertained by drawing a line, CG5, through the inter- 
section of the outside lap and valve circles, where the 




va(ve Tnavet 



A- 



FIGURE 75. 



valve is on its return movement. Thus far no account 
has been taken of release and compression, and in order 
to determine the position of the crank when these events 
occur it will be necessary to draw the valve circle for the 



130 THE WALSCHAERT VALVE GEAR 

opposite movement of the valve, for, be it remembered, 
that the movement of the valve so far considered has 
been only one-half of its travel, that is, it has moved 
from its central position towards the head end of the 
cylinder, and back again. We have seen how it has per- 
forms i the functions of admission, full port opening, and 
cut-off for the crank end of the cylinder, and now by 
reference to Fig. 75 it will be seen at what points of the 
stroke the remaining events, viz., release and compres- 
sion, occur. 

Draw a second valve circle, Fig. 75, diametrally oppo- 
site the first. Also draw an arc with a radius equal to 
the inside lap, which in this case is assumed to be one- 
half inch. When the crank gets to the position 7 its cen- 
ter line, cuts the intersection of the inside lap and valve 
circles and release begins. When the crank arrives on 
the center 8, the valve has moved the distance CT from 
central position ; but CX of this distance has been occu- 
pied by the inside lap, therefore the lead on the exhaust is 
represented by the distance XT. When the crank on its 
return stroke arrives at the position marked 10, its line 
again cuts the intersection of the inside lap and valve 
circles and compression takes place. By dropping perpen- 
diculars from the positions of the crank at 1, 5, 7, 8 and 
10 an indicator diagram may be drawn showing the per- 
formance of an engine with this style of valve. 

Fig. 76 shows the effect of decreasing the angular ad- 
vance, that is, setting the eccentric back towards the 
crank. 

In this instance the eccentric is set back 10 degrees, 
thus making the angle of advance 20 degrees instead of 
30 degrees as before. The full lines represent the new 
angle, while the dotted circles and lines indicate the valve, 
and its movements as drawn at first. 



VALVE DIAGPAMS 



131 



A shows the original point of admission, and A' the 
position of the crank when admission takes place with the 
lesser angle of advance. Similarly R and R' show the 
old and new points of release, and C and C the compres- 
sion. The two different points of cut-off are also indi- 
cated. 




FIGURE 76. 



The effect of decreasing the valve's travel is illustrated 
by Fig. jj, the full lines showing the decreased travel and 
its influence, and the dotted lines showing the original. 
Admission and release occur later, while cut-off and com- 
pression take place earlier. 



132 



THE WALSCHAERT VALVE GEAR 



The travel of the valve as indicated in Fig. yy has been 
decreased one inch, thus making it 3>4 in place of 4>4 
inches as before. Fig. 78 shows the result of increasing 
the outside lap. The lap has been increased in this in- 



C ' 



n A 



\& 



# 



17 



K<~' 



\ 



FIGURE 77. 



stance from 1 inch, as originally drawn, to lj4 as indi- 
cated by the full lines, while the dotted lines show the 
lap as it was before being changed. The effect of this 
change is to cause less lead, a later admission and an 
earlier cut-off, but compression and release are not af- 



VALVE DIAGRAMS 133 

fected, for the reason that these latter events are con- 
trolled by the inside lap, which has not been changed. 

In Fig. 75 the valve is shown as cutting off the steam 
when the crank has completed 120 degrees or two-thirds 
of the half revolution, but the point of cut-off on the indi- 
cator diagram shows that the piston has traveled 7-9 of 
the stroke. 




FIGURE 78. 



This discrepancy is due to the obliquity of the connect- 
ing rod, as it will be seen by looking at the valve dia- 
gram (Fig. 75), that the crank must travel farther to 
complete the stroke from this point than the piston does. 



134 



THE WALSCHAERT VALVE GEAR 



In order to cause the valve to cut off earlier, say, at 
one-half stroke, it will be necessary to do one of two 
things, either to increase the outside lap, which would 
have a tendency to cause admission to occur too late, or 




FIGURE 79. 



the angle of advance may be increased sufficient to cause 
cut-off to take place at half stroke, but to do this alone 
would cause admission to occur too early. Therefore the 
proper thing to do is to increase both the angle of ad- 
vance and the outside lap. Fig. 79 shows how this can 



VALVE DIAGRAMS 135 

be done without decreasing the travel of the valve. The 
angle of advance, ABC, is now 50 , where before it was 
30 , as in Fig. 75. 

The valve is central when the crank is at position 1 ; 
the high point of the eccentric being at point 4. The 
outside lap which before was 1 inch had 7-16 inch added 
to it, making it 1 7-16 inches. When the crank gets to D 
the port is just commencing to open, and with the crank 
on the center at 2, the lead is Y\ inch. 

It will readily be seen at this point that by increasing 
the outside lap still more the lead can be diminished, and 
the point of cut-off made still earlier, but this w^ould 
result in a still further reduction of the power of the 
engine, which has already been considerably reduced, as 
shown by the diminished area of the indicator diagram as 
compared w r ith the one in Fig. 67. When the crank gets 
to position 3 the valve has reached the limit of its travel, 
and the port is open the distance Aa, which is as far as 
the outside lap will permit. With the crank at point 4 
cut-off occurs. But with the increased angular advance 
iand the inside lap remaining as it was before, viz., )/z 
inch, release would occur too early. Therefore it will be 
necessary to increase the inside lap sufficient to cause re- 
lease and compression to take place at as near the proper 
points as possible. In this instance }i inch has been 
added, making the inside lap % inch, and release takes 
place with the crank at position 5, while compression 
begins at 6. 

These points, viz., release and compression, may also 
be changed by simply adding to, or decreasing the inside 
lap. It should be noted that in the foregoing discussion 
of valve gear it is understood that the valve stem moves 
in the same direction as the eccentric rod does, that is 
the direction of motion is not reversed by a rocker arm 



136 



THE WALSCHAERT VALVE GEAR 



interposed between the eccentric and the valve. In other 
words, the motion is direct. In case the motion is re- 
versed by a rocker arm (indirect motion) it will be neces- 
sary to set the eccentric behind the crank. 



3/ea 




FIGURE 80. 



Fig. 80 is a combination of the Releaux and Zeuner 
diagrams used to represent the different valve events. 

This cut, together w T ith Fig. 81 and the explanation 
following is presented by Mr. Carl J. Mellin, Consulting 
Engineer for the American Locomotive Company, and if 
closely followed will serve to still more clearly fix in the 
mind of the student an understanding of the action of 
the valve in the performance of its various functions. 



VALVE DIAGRAMS 



131 



Referring to Fig. 80, the distance AB represents the 
travel of the valve as well as the stroke of the engine, 
though in different scales, which makes no difference 
when the cut-off is always expressed in fractions or per 
cent of AB. The maximum cut-off is determined upon 
to be AR. Draw a perpendicular line RC from AB until 




FIGURE 81. 



it cuts the arc ACB. Xext decide on a desired lead and 
with that as a radius, draw an arc with A as a center. 
Draw a line from C tangent to the lead circle around A, 
when the lap of the valve is found to be equal to the per- 
pendicular distance from the line CS to the center O of 
the diagram. The crank will then be in position OS when 
the valve commences to open, or the angle AOS in ad- 



138 THE WALSCHAERT VALVE GEAR 

vance of the dead center, and on OC at cut-off. Con- 
tinuing, we find the valve in its middle position when the 
crank is on OG which is drawn parallel to SC through 
the center O. Extend this line to F, and with the exhaust 
lap as a radius draw the exhaust lap circle on the opposite 
side of the line GF and draw DE tangent to this circle, 
when OD is the position of the crank at the release point. 
From this point the exhaust remains open until the crank 
reaches the position OE, when it closes and compression 
takes place until it again reaches OS for admission and 
one revolution is completed. 

By placing the Zeuner diagram upon this, draw HJ 
perpendicular to FG, and with the radius OH of the 
eccentric circle as a diameter, draw T the admission valve 
circle OVHnO and the lap circle with the steam lap as a 
radius and find the intersection occurs at V, both with the 
circles and the previously laid down admission line OS 
and the cut-off point at the intersections at n. On the 
line OH set off the width of the steam port from L 
toward H equal to Lm and with Om as radius draw the 
arc KmK 1 . The shaded figure enclosed by the letters 
VKK 1 nL represents the steam port opening during the 
admission period and the width of the port opening at any 
desired position of the crank is found by measuring the 
distance radially from O between the lap and valve circles 
on the port line, as the case may be, on the desired crank 
position. 

The exhaust openings are determined in the same man- 
ner and are shown on opposite side of FG, where the 
crank passes through the arc DJE during the exhaust 
period with a positive exhaust lap of the size EF. When 
the exhaust edge of the valve is line and line this arc 
becomes GJF or 180 degrees, and when a negative lap 
(clearance) occurs, the duration of the exhaust period 



VALVE DIAGRAMS 139 

exceeds the half revolution of the crank. The various 
events are indicated around the eccentric circle on the 
figure as they take place during a complete turn of the 
crank. 

In Fig. 8 1 the eccentric and admission valve circles are 
shown at different cut-offs where each set of lines and 
circles is governed by the same explanation as those of 
Fig. 80, where the admission points S, S 1 , S 2 , S 3 corres- 
pond to the closing positions C, C 1 , C 2 , C 3 , cut-off points 
R, R\ R 2 , R 3 , etc. On OH we have the full travel 
valve circle and OL the lap or radius of the lap circle, 
the latter being the same for all cut-offs as well as the 
lead, the radii H 1 , H 2 , H 3 , etc., of the eccentric circles 
or diameters of the corresponding valve circles terminate 
on a line HI drawn perpendicular to AB and at a dis- 
tance from O equal to that of lap and lead. 

When the reverse lever is in its center position the 
diameter of the valve circle falls on the line AB and is 
equal to lap and lead. Continuing in back position w r e 
have the same method repeated and OI would be the 
full travel valve circle diameter, or the same as the ec- 
centric radius for the valve travel. Any desired cut-off 
position may be laid out in same manner as that in Fig. 
JJ, which shows all the valve events for a complete 
revolution of the axle. 

The movements are in actual practice pot so regular 
as the circles indicate, as it is impracticable to obtain 
the various loci in their theoretical positions ; besides 
we have the angularities both of the main rods and the 
eccentric rods to contend with and whereby irregularities 
are entering in the problem that must be compensated 
for, as referred to in the general description. It is not 
to be considered that a uniform circular motion is the 
best, but an approximation to it works with less shocks 



140 



THE WALSCHAERT VALVE GEAR 



or jerks, and is therefore more desirable for so high 
speed an engine as a locomotive. A few advantages 
can be taken, however, in selecting the suspensions and 
various connections, so that better results can be ob- 




FIGURE 82. 



K- Id/amr- 



A CONVENIENT GAUGE FOR SETTING THE 
ECCENTRIC CRANK. 



tained than from a true circular motion, which are 
principally affected by three union points and are, first, 
the connecting point of eccentric rod and link; second, 
the locus of the lifting link suspension point; and third, 
the relative height of the crosshead connection point of 
the union bar to the corresponding point of the combina- 
tion lever. 



VALVE DIAGRAMS 



141 



It is not necessary to lay out the valve diagrams ex- 
cept where a given cut-off per cent, is wanted. This 
is the most convenient way to find the required lap. 

Reason for Increase of Lead as Reverse Lever is 
Locked Back with Stevenson Valve Gear. 

The explanation of this problem, although simple 
enough, is generally presented to the student by techni- 
cal writers in such a form as to be incomprehensible to 
the man with limited education, therefore the author 
considers it his duty to explain in as clear a manner as 
possible the causes of this very annoying, but inevitable 
occurence. 




FIGURE 83. 



Lead is the amount of opening that the valve gives 
to the steam port when the engine is on the dead center, 
that is with the piston at the extreme end of the stroke, 
and this lead is obtained by advancing the eccentric the 
required number of degrees ahead of the crank in the 
direction it is to run. 

Referring to Fig. 83, let a, represent the locus of the 
eccentric and eccentric strap with the reverse lever in 
the position of full valve travel. Now as the lever is 



142 THE WALSCHAERT VALVE GEAR 

hooked back to shorten valve travel the eccentric rod 
is raised, and the eccentric strap is moved back on the 
eccentric, which would increase the lead to the same 
amount as moving the eccentric ahead on the driving 
axle would. Mark a, would now be broken, as at b. 

The amount that the lead is increased depends to 
some extent upon the length of the eccentric rods, as 
with long rods the lead will not be affected so much, 
as with short rods. But with Walschaert Valve Gear 
the lead is constant at all points of cut-off, for the reason 
that it is derived through the crosshead connection, of 
the combination lever actuated by the reciprocating mo- 
tion of the piston, instead of by the circular motion of 
the driving axle transformed into a reciprocating motion 
through the instrumentality of rods accompanied w T ith 
all of the errors incidental to their angularity. When 
an outside admission valve is used the upper end of 
the combination lever is connected directly to the valve 
stem, while the radius rod connection is between the 
valve stem, and crosshead connections, and acts as the 
fulcrum for the combination lever. When the valve is 
of the inside admission type, these connections are re- 
versed, the upper end of the combination lever being 
connected to the radius bar, while the valve stem con- 
nection lies between the crosshead connection below, and 
the radius bar connection above. The motion thus im- 
parted to the valve stem by the combination lever when 
the position is at the extremities of the stroke, and the 
eccentric crank in its middle position is uniform, and 
so modifies the motion received from the eccentric crank 
through the medium of the link and radius bar, as to 
give the valve a constant lead at all times, for either 
the go-ahead, or back-up motion. 

The connection of the radius bar with the combina- 



VALVE DIAGRAMS 143 

tion lever, always forms the fulcrum of the lever. If 
this fulcrum is below the connection of the lever with 
the valve stem, it is plainly evident that the motion of 
the crosshead when nearing the end of the stroke, will 
through the medium of the long arm of the combination 
lever which is attached to it, push the valve stem in the 
direction that the piston is to move on the return stroke, 
thus giving the correct lead for an outside admission 
valve. 

On the other hand if this fulcrum is above the con- 
nection of the valve stem with the combination lever, 
the valve stem will be drawn by the lever in the direc- 
tion opposite to that in which the piston is to move on 
the return stroke, and this movement will impart the 
proper lead for an inside admission valve. 

The proportions of the combination lever are such 
that, given the stroke of the piston, a motion equal to 
the lap, and lead, is imparted by the combination lever to 
the valve as the crosshead is moved from one end of the 
stroke to the other. As before stated the length of the 
radius bar should be equal to the radius of the link. 



DETAILS OF OPERATION. 

The requirements of modern railway service in all its 
branches, but especially in the department of motive 
power have reached that condition wherein the best of 
everything is needed. 

In this the Walschaert Valve Gear is demonstrating 
day by day that it is fully capable of holding its own 
indefinitely, not only as regards economy but also in the 
matter of reliability, and freedom from annoying break- 
downs, or disarrangement of parts. The first requisite 
is that it be correctly designed and constructed to meet 
the requirements of each particular type of engine, and 
class of service. 

The second requisite is that it be accurately adjusted 
before the engine leaves the shop, as it is not possible 
to make any changes in adjustment while out on the 
road, with the exception of a slight change in the length 
of the eccentric rod. 

The third requisite is that it be well cared for on the 
route. This regulation applies to any valve gear, and 
implies that it be properly lubricated, and that it, and all 
other working parts of the engine in general, and the 
driving boxes in particular be kept free from lost 
motion. 

Owing to the small amount of friction, in the Wal- 
schaert valve gear it is not nearly so liable to heat as 
is the Stevenson link motion, and besides this it has the 
advantage of being outside the frame in full view of the 
enginemen, which cannot be said of the Stevenson gear. 

It has been demonstrated bevond all doubt that the 

144 



DETAILS OF OPERATION 145 

Walschaert gear will withstand a much longer term of 
service between shop repairs than the Stevenson valve 
gear will, and this fact is easily accounted for when 
we consider the difference in weight between the two 
types of valve gear. 

In this connection it might be well to quote from a 
paper read before the International Railway Congress 
by Mr. F. C. Muhlfeld. 

With reference to the weight, friction, liability to 
heat, wear, breakage, etc., Mr. Muhlfeld says: 

''When comparison is made between the weight of the 
moving parts and the size of the bearings of the Wal- 
schaert outside gear with similar parts of the Stephen- 
son inside gear, it will be found that a simple design of 
the latter weighs more than double the amount of the 
former, and is becoming a very cumbersome and heavy 
suspended reciprocating and revolving arrangement. The 
increased complication and weight of the Stephenson 
gear has resulted in a distorted steam distribution, to 
say nothing of the destructive effect of the heavy parts 
and the increased cost for maintenance on account of 
excessive wear and breakage. The eccentrics and straps 
have not only to carry the increased friction of the larger 
sizes of valves, but the reversing twice for every revolu- 
tion and the inertia of the reciprocating parts of the gear 
has contained the principal load, and they have become 
one of the troublesome details of locomotive machinery, 
requiring constant inspection and maintenance attention 
to prevent liability of heating or failure. Furthermore, 
the inaccessibility of the entire arrangement, due to its 
location within the frames, makes proper attention almost 
impracticable in connection with the modern locomotive 
dispatchment conditions. 

"A motion placed outside of the frames certainly has 



146 THE WALSCHAERT VALVE GEAR 

the advantage of accessibility and convenience for in- 
spection, lubrication, repairs and cleaning, and the Wal- 
schaert type provides for this and gives an opportunity 
for better diagonal and cross bracing which is so neces- 
sary between the main frames and the frames and boilers, 
to maintain alignment and stability and reduce frame 
failures. 

"The Walschaert gear has long been popular in France, 
Germany, Belgium, and other foreign countries, and it 
is used extensively on compound and simple types of 
locomotives for high and low speeds. It can be made 
of comparatively light parts, and having no angular 
advance and no lead that can be given other than by 
the crank arm, a valve movement can be produced that 
is equivalent to that given by an eccentric having an- 
gular advance. 

"Unless improvement can be effected in the design 
and application of the Stephenson motion, it will be 
necessary to inaugurate the use of the Walschaert or 
some similar type of gear for the modern locomotive 
construction in this country to insure the best results 
from high pressure with a single valve having large 
port openings and rapid movement for admission and 
exhaust, delayed opening of exhaust port for longer 
expansion and initial expansion, and effective action on 
crank when the angularity of the main rod and piston 
pressure is most favorable to produce the greatest degree 
of efficiency as well as economy at high and low speeds." 

The operation of the Walschaert valve gear is not dis- 
turbed by the vibration, up and down, of the engine upon 
its springs, to the extent that the Stevenson valve gear 
is, provided of course that the point of connection of 
the eccentric rod, and the link is as near the center line 
of motion of the main rod as it is possible to locate 



DETAILS OF OPERATION 147 

it. Great care should be exercised in adjusting a valve 
gear to see that the valve is in the center of its travel, 
when the piston is at mid-stroke and the reverse lever 
is in the middle or central notch of the quadrant. The 
position of mid-stroke for the piston does not necessarily 
imply that the center of the crank pin is perpendicular 
above or below the center of the driving axle. 

On the contrary, owing to the angularity of the main 
rod, the position of the crank pin, with the piston at mid- 
stroke, will be a slight distance to one side of a perpen- 
dicular line cast through the center of the driving axle, 
the distance depending upon the length of the rod. The 
longer the rod the less this distance will be. 

The main pin will in this position be on what is termed 
the working quarter, the center of the crosshead pin will 
be at the center of its travel or mid-stroke, and the com- 
bination lever of the Walschaert valve gear will be in a 
perpendicular position, which can be ascertained by drop- 
ping a plumb line from the center of the connection of 
valve stem and combination lever, to the center of the 
connection of crosshead and combination lever. 

With the reverse lever in the central notch, the centers 
of the link fulcrum pin, and link-block pin, should ex- 
actly coincide. If they do not it is an indication that 
the center notch of the quadrant is not properly located, 
and this defect should be remedied at once before pro- 
ceeding to test the correctness of the valve's position. 

Having finally succeeded in getting all of the other 
parts correctly located, an off hand test of the valve 
may be made as follows : If with the cylinder cocks 
open, the piston at mid-stroke as just described, and 
reverse lever in center notch, a slight opening of the 
throttle causes the steam to blow from one of the 



148 THE WALSCHAERT VALVE GEAR 

cylinder cocks on that side of the engine, it is an indica- 
tion that the valve is not at mid-travel, and that it does 
not cover the admission ports. Which port is uncovered 
will be shown by the cylinder cock from which the steam 
is blowing. 

The cause of an error like this in the position of the 
valve, and the proper remedy for it can only be de- 
termined by careful experiment. First it might be cor- 
rected by a slight change in the length of the valve stem, 
but this should be proceeded with very carefully. 
Secondly, the link bearer, which is usually attached to 
the guides, may possibly not be in its true position and 
may require to be moved either back or forward a slight 
distance. 

This latter move is liable to cause another error, how- 
ever, due to the fact that it changes the distance between 
the link fulcrum and the eccentric. 

But this fault can be easily corrected by adjusting 
the length of the eccentric rod. Any changes in the 
Walschaert valve gear, after the engine has been turned 
out of the back shop, sliould be proceeded with carefully, 
always bearing in mind that this gear from the link for- 
ward is permanently located, all motion bearers as a rule 
being attached to the guides. Back of the link, however, 
slight changes in distances may be made when necessary 
to take up lost motion due to wear. 

The necessity of correcting the length of the eccentric 
rods may be ascertained by the following method: 

Place the engine with one side on the forward dead 
center, and the reverse lever down in the go-ahead corner 
notch. Then have a helper slowly move the reverse lever 
back towards the center notch of the quadrant. Watch 
the valve stem closely while the link block is rising, 



DETAILS OF OPERATION 149 

and if the stem is pushed forward slightly, it is an indi- 
cation that the eccentric rod needs to be lengthened. 

On the other hand if the valve stem is drawn back- 
wards by the rising link-block, the eccentric rod should 
be made slightly shorter. Very slight changes in either 
case should be made in the length of the rod. It is better 
to make several tests of hooking up the reverse lever 
to the center notch, and slightly changing the length of 
the rod as required at each test. Finally when, by mov- 
ing the reverse lever from the corner notch back to 
the center notch, with the engine in the position as in- 
dicated above, neither valve stem nor radius rod is 
affected, the adjustment for that side of the engine may 
be considered correct. The same method of testing 
should be followed on the other side, with the exception 
that the engine be placed on the back dead center. The 
facilities for making changes in the length of the ec- 
centric rods on modern locomotives, equipped with the 
Walschaert gear appear to indicate plainly that it is a 
"back shop" job in most cases, 

One very important feature connected with the suc- 
cessful operation of the Walschaert valve gear, is that 
the bracket supporting the link trunnion should be 
permanently fixed at an unchangeable distance from the 
cylinder, and valve chest, and in order to accomplish 
this it is necessary that this bracket be firmly attached 
to the guide yoke or bearer. 

The valve stem slide which supports the combination 
lever, and forward end of the radius bar, represents 
another point which permits of no variation in distances, 
and for this reason it also is securely attached to the 
guides. 

A discussion of the operation of the Walschaert 
valve gear would not be complete without a reference 



150 THE WALSCHAERT VALVE GEAR 

to the subject of breakdowns and their remedies, and 
in treating this subject we will start with the eccentric 
crank, that being the prime mover, and main source of 
motion for the other parts of the gear. In this connec- 
tion it may be well to note, particularly, an advantage 
possessed by this gear over the Stephenson link, viz., that 
the eccentric is invariably attached to, and derives its 
motion from the main driving axle, through the medium j 
of the main crank pin. This cannot be said of the 
Stevenson gear, as on some types of engines the ec- 
centrics are not located on the main axle, but on one of 
the other axles. Especially is this the case with engines 
having three or more pairs of driving wheels. 

The breaking of a side rod on an engine of this type . 
equipped with the Stephenson link would totally disable 
the engine, for the reason that the driving axle carrying 
the eccentrics would not remain in accord with the main 
driving axle, and crank pin still being driven by the main 
rod. With the Walschaert valve gear the breaking or 
removal of a side rod does not totally disable the engine, 
for the reason as before stated, that the eccentric is 
actuated by the main crank pin, and the engine on the 
uninjured side of the locomotive could still be operated. 

In case an eccentric crank, or eccentric rod of a Wal- 
schaert valve gear should break or become disabled in 
any way, the broken parts should be removed, then lower 
the link block and radius bar to the bottom of the link, 
after doing which disconnect the suspension bar from 
the radius bar, also disconnect the radius bar from the 
combination lever, and raise the front end of the radius 
bar clear of interference, and firmly secure it by wiring 
through the pin hole, and to any convenient and solid 
part of the engine. This should be done in order to 
prevent the link from vibrating with the motion of the 



DETAILS OF OPERATION 151 

engine. Having thus secured the link and radius bar, 
the next move is to block the valve, the methods of 
doing which will be described later on. Very often a 
breakdown occurs with some part of the engine that will 
prevent the working of steam on that side, despite the 
fact that the valve gear is intact. In such cases it will 
be necessary to block the valve to prevent admission ot 
steam to the cylinder, while at the same time the other 
parts of the valve gear need not be wholly taken down 
or disconnected, excepting of course the radius bar, which 
should always be disconnected at least, at the front end 
when it becomes necessary to block the valve. 

In case a breakdown of this character should occur, 
with the engine having but a short distance to travel to 
reach its terminal station, a quick method of solving 
the problem w T ould be to block the valve, disconnect the 
radius rod at the front end, and suspend the rod by a 
pendulum of strong wire or rope passed through the pin 
hole, and attached to some point above in such a manner 
as to allow the rod to swing freely back and forth with 
the motion of the link. Care should be exercised to 
see that the suspended end of the radius bar does not 
strike anything in its vibrations. However this method 
should not be pursued, except as before stated, when 
the engine has but a short distance to run. A much 
safer method, and one which will permit the engine to 
be speeded up, and run for a long distance with one 
side disabled, would be as follows : 

Locate the link block and back end of the radius bar 
in the exact center of the link by placing the reverse 
lever in the center notch of the quadrant. Then cut two 
blocks of wood of the proper dimensions to fit and place 
them between the lower part of the link and the link 



152 THE WALSCHAERT VALVE GEAR 

block for the purpose of supporting the link block in 
the center. 

These blocks should be secured by lashing with 
wire or rope. Xext disconnect the hanger between the 
lifting arm, and radius bar, also disconnect the front 
end of the latter, from the combination lever, and wire 
the radius bar up as previously directed, or suspend it 
in any way that will support it securely, there being no 
motion imparted to it so long as the link block, with the 
back end of the radius bar, remains at the center of the 
link. 

It is not necessary in all cases to disconnect the com- 
bination lever as the motion imparted to its lower end 
by the crosshead is not likely to disturb the valve, but 
the precaution should be taken to watch the first move- 
ment of the crosshead and see that the combination lever 
does not strike the crosshead pin, since the motion of 
the lever may be slightly changed by the disconnection 
of its upper end. 

A good plan is to carry wood blocks on the engine of 
the proper shape and dimensions, to hold the link block, 
and radius bar at the center of the link. They will then 
be available at any time that it is desirable to carry the 
link block and radius bar without motion. 

It should be remembered that in this discussion of 
rules for guidance in case of breakdowns, there is always 
one feature that must not be neglected, viz., the placing 
of the valve in the center of its travel in order to prevent 
admission of steam to the cylinder of the disabled side. 
This applies always in case of breakdowns when it is 
desired to proceed with one side disabled. In the case 
of a broken radius bar, the pieces of the broken bar 
should aill be taken down, except possibly in case there 
should be enough left of the bar forward of the link to 



DETAILS OF OPERATION 153 

make it safe to block it up in the center of the link as 
heretofore described, and suspend or secure the front 
end of the bar. The location of the lifting arm, or sus- 
pension bar of the Walschaert valve gear is governed 
by the type of engine to which it is applied. On some 
engines it is connected to an extension of the radius bar 
back of the link, and on others it is connected to the 
bar forward of the link. In case the lifting arm should 
break, or the extension of the radius bar back of the 
link should become bent or broken from any cause, while 
the connection of the radius bar to the link block still 
remained intact, the following method may be pursued : 

Assuming that the engine is to run forward, first place 
the reverse lever in the notch that it will be expected to 
work in. Then note the height of the link block from 
the bottom of the link on the side of the engine that is 
not disabled. Next place a short block in the link under 
the radius rod, or the link block on the disabled side, 
this block being of a length sufficient to raise the radius 
bar and link block to about the same height in the link 
as the one on the other side is. All broken parts should 
be removed and another block placed in the link above 
the link block or radius bar to prevent them from slip- 
ping up in the link. Having thus secured all parts, the 
engine may be operated, always bearing in mind however 
that the reverse lever must not be moved from the notch 
at first chosen, neither hooked up, nor dropped lower, 
so long as the engine is working with one of the lifters 
disabled. 

When a valve stem breaks disconnect the radius bar 
and secure it in the manner already described. Then 
place the valve in its central position and block or clamp 
it there. The combination lever may be left in place, 
provided that its lower portion does not strike the cross- 



154 THE WALSCHAERT VALVE GEAR 

head pin in its travels. As has been stated, the motion 
of the combination lever is liable to be changed slightly, 
due to its having been disconnected at the top from the 
radius bar, but in case of a broken valve stem, the slide 
from which the valve stem has been disconnected by the 
breakage, and to- which the combination lever is still 
connected, may now be placed, and secured in any posi- 
tion on the slide bar, that offers the safest motion to 
the combination lever, and it should then be blocked in 
that position in order to preclude any possible chance of 
its being moved by the combination lever to such an ex- 
tent as to affect the valve in the least, or push it off 
center. 

In case the combination lever, or the short bar con- 
necting it to the crosshead should get broken or bent, 
the pieces should be removed, and the radius bar dis- 
connected, and dealt with in the manner already ex- 
plained, after which the valve should be placed at mid 
travel and blocked. When an engine that is equipped 
with the Walschaert valve gear, is disabled on account 
of a broken main rod, and no other parts of the engine 
have been disabled or broken, one of the first things to 
do is to disconnect the radius rod and secure it in the 
manner heretofore outlined. Then if the valve is of the 
inside admission type, it should be pushed to the for- 
ward end of the valve chest and secured by a clamp on 
the stem, or it may be blocked at the slide, to hold it in 
that position. 

If the valve is an outside admission valve it should 
be secured at the back end of the valve chest in such a 
manner as to prevent it from moving. The object aimed 
at in securing the valve, in either case, is to keep open 
the admission port for the front end of the cylinder, 
in order to permit the steam to enter the cylinder through 



DETAILS OF OPERATION 155 

that port, while the back port is kept open to the ex- 
haust. 

The next move is to draw the crosshead towards the 
back end of the guides as far as it will go, or until the 
piston is up snugly against the back cylinder head, and 
there block the crosshead. This will hold the piston 
firmly in that position, whether the throttle is open or 
closed, and there will be no danger of its moving. 

Of course, when the trottle is open, the piston will 
be blocked by the steam admitted through the front port, 
but in drifting down hill, or if the engine should receive 
a sudden jerk caused by an application of the air brakes, 
or from* any other cause, there is danger of the piston 
slamming up against the front cylinder head, unless the 
crosshead is securely blocked. 

The combination lever need not be disturbed. If the 
eccentric crank and rod have not been damaged in any 
way they may also be left in position, as the motion im- 
parted to the link by the eccentric rod will do no harm, 
so long as the radius bar is properly suspended. 

Having removed the parts of the broken main rod, 
and attended to the above described details, the engine is 
ready to proceed, with one side in working condition. 

If a piston gets broken, or disconnected from the 
piston rod, the usual result is that the front cylinder 
head also gets broken. Whether the front head is broken 
or not it should always be removed, and the broken 
piston taken out of the cylinder. If the piston rod is 
not broken the main rod may be left up, but the radius 
bar must be disconnected, and secured, and the valve 
centered and blocked. The engine is now ready to go, 
provided the piston rod has not been bent, but if the 
rod is bent in the least, the main rod should be taken 
down also, and the crosshead be blocked in the manner 



156 THE WALSCHAERT VALVE GEAR 

already recommended. In case a front cylinder head is 
broken, or blown out, the radius bar should be discon- 
nected, as usual, and the valve centered. The back 
cylinder cock should be removed, also, in order to pre- 
vent the formation of a vacuum behind the piston in 
its travels, and also to allow any water of condensation 
to escape. The lubrication of the piston with the front 
cylinder head removed becomes an easy problem. 

If the back cylinder head should get broken or blown 
out, an accident which fortunately does not occur very 
often, the main rod should be taken down, as it would 
not be safe to take any chances on the piston rod having 
been bent when the cylinder head was broken. 

If the breakdown is not serious as for instance a piece 
broken out but still leaving the head strong enough to 
withstand the pressure of the piston against it, while 
under steam, the same method may be pursued as in 
the case of a broken main rod, viz., blocking the piston 
with steam admitted through the front port, also block- 
ing the crosshead. 

In case the back cylinder head is broken very badly, 
in fact rendered entirely useless except for scrap, the 
main rod should be taken down, the radius bar dis- 
connected, and secured as already explained, and the 
valve placed at mid travel, and blocked. 

If at any time it should happen that the short con- 
necting bar between the crosshead and the lower end 
of the combination lever, should get broken, and lost, 
from both sides of the engine, and it is desired to obtain 
the lengths of the lost bars, the following method may 
be resorted to, and it will give at least a close approxima- 
tion : 

Place the crosshead at mid travel, in that position 
which w r ould indicate that the piston is at mid stroke. 



DETAILS OF OPERATION 157 

Then place the reverse lever in the center notch of the 
quadrant, which should bring the link blockpin and the 
link fulcrum pin or trunnion center to center. 

When the above mentioned parts are in the positions 
designated, viz., the piston at mid stroke, and the link 
block, and link trunnion centers together, the long arm 
of the combination lever should hang perpendicular, and 
it may be placed in this position by the use of a plumb 
line, after which the length of the lost bar may be ob- 
tained by taking the distance from the center of the 
pin in combination lever to the center of the pin in the 
arm on the crosshead, to which the short bar is con- 
nected. 



EXAMINATION QUESTIONS. 

i. What is the chief difference between the Wal- 
schaert, and the Stephenson valve gears? 

2. How is the Walschaert gear operated? 

3. How is the link secured? 

4. Describe in general terms the construction, and 
operation of the radius rod and link. 

5. Is a rock shaft always necessary with the Wal- 
schaert valve gear? 

6. What is the function of the combining levers? 

7. Describe the connection, and operation of this 
lever. 

8. Where is the fulcrum of the combination lever 
with outside admission valves? 

9. With inside admission valves where is the fulcrum 
located ? 

10. What should the radius of the link be equal to? 

11. How can this be ascertained? 

12. What are the two essential points to be kept in 
view in the design and construction of the Walschaert 
valve gear? 

13. If, after connecting the gear there should be a 
slight variation between the forward and backward posi- 
tion of the valve how may it be corrected? 

14. What disadvantage attends the investigation of 
the Stephenson valve gear on a modern locomotive when 
out on the road? 

15. How many eccentrics, or eccentric cranks are re- 
quired to drive the Walschaert valve gear? 

16. How does this gear compare with the Stephen- 
son gear, in the items of size of bearings, and friction? 

158 



EXAMINATION QUESTIONS 159 

17. Does the lead of the valve vary^ at different points 
of cut-off with the Walschaert gear? 

18. Mention some of the advantages to be gained by 
a constant lead. 

19. Is the Walschaert valve gear as easy to handle 
from the cab as is the Stephenson? 

20. Has the valve gear of locomotives kept pace 
with other parts in general development and improve- 
ment? 

21. Owing to the demands of modern transportation, 
what can be said of the Walschaert valve gear? 

22. What are its advantages over the Stephenson gear 
as regards accessibility? 

23. What is the saving in weight effected by the use 
of the Walschaert gear? 

24. What can be said of this gear as regards direct- 
ness of transmission? 

25. As to permanence of adjustment? 

26. How does it compare with the Stephenson gear 
in the matter of wear? 

27. In regard to smooth operation what can be said 
of the Walschaert gear? 

28. How is the frame bracing affected by the use 
of this valve gear? 

29. In the construction of the Walschaert valve gear 
how are the proportions of the combination lever de- 
termined ? 

30. What factors govern the location of the link? 

31. What rules are to be observed in the location of 
the suspension point of the lifter? 

32. In the location of the longitudinal position of 
the link fulcrum, what points are to be considered? 

33. Where should the point of connection between 
the eccentric rod and the link be located? 



160 THE WALSCHAERT VALVE GEAR 

34. If this location should cause too much eccentric 
throw, how may a compromise be affected? 

35. What important rule should govern the laying 
out, and construction of the Walschaert valve gear ? 

36. Why should this rule be strictly observed? 

37. Is there any part of this gear in which changes 
may be made, once it is erected? 

38. What form does the eccentric usually assume in 
the Walschaert valve gear? 

39. What is the position of the center of the eccen- 
tric crank relative to the plane of motion? 

40. Has the eccentric an angular advance? 

41. Does the Walschaert valve gear lend itself as 
freely to adjustment as does the Stephenson link? 

42. What great advantage has the Walschaert gear 
over the Stephenson gear as regards the lead given the 
valve ? 

43. What motion controls the lead? 

44. What motion controls the valve travel and re- 
versing operations ? 

45. Where would the motion of the eccentric alone 
place the valve when the piston is at the end of the 
stroke ? 

46. Wherein does the reversing operation of the Wal- 
schaert valve gear differ from that of the Stephenson 
link? 

47. What precaution should be observed regarding 
the position and throw of the eccentric when the engine 
is assembled? 

48. How is the amount of lap and lead ascertained? 

49. In the adjustment of this valve gear, how 7 is the 
length of the eccentric rod determined? 

50. What should be done with the valve stem before 
changing the eccentric rod ? 



EXAMINATION QUESTIONS 161 

51. What does the difference between the two posi- 
tions of the valve on the forward and back centers repre- 
sent ? 

52. Can this be changed? 

53. How is the lead equalized for both ends? 

54. How may the lead be increased ? 

55. Referring to Special Instructions by the Baldwin 
Locomotive Co. regarding the erection of the Walschaert 
valve gear, what precautions are to be taken as to the 
dimensions of the various parts? 

56. What should be done with the eccentric? 

57. What suggestion is made concerning the guide 
bearer? 

58. What should be done regarding the location of 
the link? 

59. What is said concerning the reverse shaft, lifting 
arm and link? 

60. Concerning connections of crosshead gear or 
combination lever, and the radius rod to the valve, what 
method should be pursued ? 

61. If any errors exist after the eccentric has been 
connected, how may they be corrected? 

62. After the valves have been adjusted, in common 
parlance, "set," how may they be tested? 

63. Referring to types of valves, what is the princi- 
pal objection to the use of the D slide valve? 

64. Is the piston valve a perfectly balanced valve ? 

65. What is a necessary factor in order that a valve 
may be perfectly balanced? 

66. Can an inside admission valve be balanced similar 
to an outside admission? 

67. Why should a piston valve be made as long as 
possible? 



162 THE WALSCHAERT VALVE GEAR 

68. Is there any particular advantage in the use of 
inside admission valves over those of outside admission? 

69. Name four simple rules by which an engineer 
may ascertain whether the valves of his engine are inside 
or outside admission. 

70. Mention a very common defect of snap-ring piston 
valves. 

71. Describe in general terms the Wilson high 
pressure valve. 

72. Is the balanced area of this valve the same at all 
points of its travel? 

73. Does the port pressure influence the balancing of 
the Wilson valve? 

74. Mention the names of five types of balanced 
valves for locomotives that are being used extensively. 

75. How may the actions of the valve and the relative 
positions of the crank pin and eccentric be illustrated? 

76. What diagrams are generally used for this pur- 
pose? 

77. Explain the reason for the increase of lead as 
the reverse lever is hooked back with the Stephenson 
valve gear. 

78. Upon what does the amount of this increase of 
lead depend? 

79. Why is there no change in the lead with the Wal- 
schaert valve gear? 

80. What part of this gear is it which forms the ful- 
crum for the combination lever? 

81. What is the first requisite to be considered in 
connection with this gear? 

82. What is the second requisite in connection with 
the operation of the Walschaert valve gear? 

83. What is implied in the third requisite? 



EXAMINATION QUESTIONS 163 

84. Does the vibration of the engine upon its springs 
disturb the Walschaert valve gear in its operation ? 

85. What precautions are to be observed in order to 
attain this object? 

86. When the piston is at mid stroke, is the crank 
pin center exactly perpendicular above, or below the 
center of the driving axle? 

87. What then is the position of the crank with the 
piston at mid stroke, and what causes it to assume that 
position ? 

88. Where will the center of the crosshead be with 
the piston at mid stroke? 

89. What should be the position of the combination 
lever of the Walschaert gear, with the piston at mid 
stroke ? 

90. How can this be ascertained? 

91. What should be the position of the link fulcrum 
pin, and the link block pin when the reverse lever is in 
the central notch of the quadrant? 

92. If these pins are not in their correct position, 
what is the probable cause of the error? 

93. How may an off hand test of the valve adjust- 
ment be made? Describe the process. 

94. If by this test the position of the valve is found 
to be wrong, how may it be righted? 

95. What precaution should be observed in regard 
to making changes in this gear after it has been turned 
out of the back shop? 

96. Describe the method of correcting the length of 
the eccentric rods. 

97. Mention a very important feature in connection 
with the link support. 

98. What other portion of this gear permits of no 
variation of distances? 



164 



THE WALSCHAERT VALVE GEAR 



99. What can foe said of the Walschaert valve gear 
regarding its source of motion, and the location of its 
eccentric crank ? 

100. Does this apply to the Stephenson gear in all 
cases ? 

10 1. What especial type of engine would be totally 
disabled by the breaking of a side rod if equipped with 
the Stevenson link ? 

102. Why should the engine be disabled? 

103. If such an engine was equipped with the Wal- 
schaert gear would such an accident disable it from pro- 
ceeding further ? 

104. Give the reason for this. 

105. In case of an accident to the eccentric crank, 
or eccentric rod of a Walschaert gear, what is the proper 
method to pursue ? 

106. If a breakdown of this kind should occur with 
the engine having but a short distance to cover to reach 
the terminal station, what would be a quick method of 
solving the problem? 

107. Is this method to be recommended at all times? 

108. Describe a much safer method which will per- 
mit the engine to be speeded up with one side after the 
job is completed. 

109. Is it necessary in all cases to disconnect the 
combination lever? 

no. What precaution must be observed in this par- 
ticular ? 

in. What is a good plan to pursue in the way of 
preparation for breakdowns? 

112. What particular feature must not be neglected 
with any kind of a breakdown when it is desired to 
proceed with one side? 



EXAMINATION QUESTIONS 165 

113. What should be done in case of a broken radius 
bar? 

114. Is the lifting arm, or suspension bar of the Wal- 
schaert valve gear always located in the same position 
relative to the link? 

115. In case the lifting arm should break, or the 
extension of the radius bar back of the link should be- 
come bent or broken while the connection of the radius 
bar to the link remained intact, what method should 
be pursued? 

116. When temporary repairs of this kind are made 
what precaution regarding the reverse lever must be 
observed ? 

117. When a valve stem breaks what may be done 
to fit the engine for running with one side? 

118. If the combination lever or its connection to 
the crosshead gets bent or broken what should be done ? 

119. What must always be done with the valve, on 
the disabled side? 

120. In case of a broken main rod what is the proper 
course of procedure? 

121. If the valve is an inside admission valve, what 
must be done with it? 

122. If the engine has outside admission valves what 
must be done with the valve? 

123. What is the object aimed at in thus securing 
the valve ? 

124. What must be done with the crosshead in case 
of a broken main rod? 

125. Why is this precaution necessary with the cross- 
head ? 

126. What must be done with a broken or discon- 
nected piston? 



166 THE WALSCHAERT VALVE GEAR 

127. Is it necessary to take down the main rod in all 
cases of a broken piston ? 

128. When is.it absolutely necessary to take down the 
main rod for a broken piston ? 

129. If a front cylinder head should get broken or 
blown out what should be done? 

130. Why should the back cylinder cock be removed 
in this case? 

131. In case a back cylinder head should get broken 
or blown out what should be done? 

132. If the break in the back cylinder head is not 
serious what may be done? 

133. What is the proper method of procedure when 
the back cylinder head is badly broken? 

134. If the connecting bar or link between the cross- 
head and the lower end of the combination lever should 
happen to get broken and lost from both sides of the 
engine, how may the lengths of the lost bars be ob- 
tained? 



SERVICE RESULTS WITH WALSCHAERT 
GEAR. 

That the advantages herein outlined for this valve are 
not merely theoretical, is indicated in the following quo- 
tations from communications from Mr. H. F. Ball, Su- 
perintendent of Motive Power of the Lake Shore & 
Michigan Southern Railway: 

"Our enginemen are very enthusiastic over the Wal- 
schaert valve gear, and we are about to arrange with the 
American Locomotive Company to equip twenty-five 
consolidation engines with it. My feeling in the matter is 
that the Walschaert gear has come to stay, particularly 
for all heavy power." 

"In reference to the Walschaert valve gear, engine No. 
912 has now a total of 1/16 in. lost motion in the valves. 
This is the total lost motion in the whole motion work. 
This engine has made approximately 39,000 miles, and 
engine No. 5924 (with link motion), examined the same 
date, had 5/16 in. lost motion in the valve stem, and has 
made approximately 32,000 miles. This seems to be very 
much in favor of the Walschaert motion/'' 

OPINION OF DR. GOSS. 

"This design (the Walschaert) makes a strong appeal 
to engineers who are forced to go outside of the frames 
with their valve motion, and for this reason its use is 
likely to increase in American practice. If, as many en- 
gineers believe, some form of balanced compound is to 
gain ascendancy in this country there will be a greater 
difficulty in retaining the valve gear between the frames." 
— Southern and Southwestern Raikvay Club. 

167 



EXAMPLES OF UNIVERSAL ADAPTABILITY. 

Mention has already been made of the ease with which 
the Walschaert valve gear can be applied to any type of 
locomotive. 

It is therefore fitting that a space be devoted to illus- 
trations and short descriptions of several of the more in- 
teresting examples of the adaptability of this valve gear 
to the varied and at the same time changing demands and 
conditions of modern locomotive practice. 

The following concerning the DeGlehn four cylinder 
compound locomotive is copied from the Railway Master 
Mechanic of August, 1907 : 

The Baldwin Locomotive Works has recently built 
twenty ten-wheel locomotives for the Paris-Orleans Rail- 
way of France. These engines are compounded on the 
DeGlehn system, and were built to drawings furnished 
by the railway company. All measurements in their con- 
struction were made on the metric system, necessitating 
the introduction by the builders, of many new standards 
and gauges. 

The DeGlehn type of locomotive is characterized by 
an arrangement of cylinders which divides the application 
of the power between two driving axles, and provides a 
separate valve gear for each cylinder, so that the high 
and low pressure cut-offs can be independently varied. 
The high pressure cylinders are placed outside, while the 
low pressure are inside between the frames. The Wals- 
chaert valve motion is used throughout. The gears for 
the inside cylinders are driven from eccentrics placed on 

168 



UNIVERSAL ADAPTABILITY 



169 




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170 THE WALSCHAERT VALVE GEAR 

the first driving axles, while those for the outside cylin- 
ders are driven from the second pair of driving wheels 
by return cranks placed on the crank pins. 

The outside, or high pressure cylinders, are connected 
to the second pair of driving wheels, while the inside, 
or low pressure, are connected to the first pair, which 
has a cranked axle. In order to keep the main rods of 
as nearly the same length and weight as possible, the 
high pressure cylinders are set some distance in the rear 
of the low pressure cylinders. This arrangement of cylin- 
ders is facilitated by the use of plate frames to which 
the cylinder castings are conveniently bolted. In the 
locomotive mentioned, the high pressure cylinders are lo- 
cated immediately in front of the leading pair of driving 
wheels. The slide valves are balanced, and are of bronze. 
The low pressure valves are also of bronze, but unbal- 
anced ; they have inclined seats, and their steam chests 
are formed within the cylinder casting. All the cylin- 
ders are set on an inclination of 3^ per cent to pro- 
vide clearance for the engine truck under the low pres- 
sure cylinders. Steam is conveyed to the high pressure 
cylinders through external pipes, and is passed on to the 
low pressure cylinders through special valves which are 
operated by air pressure controlled from the cab. 

The center lines of the high pressure steam chests are 
placed outside the cylinder center lines, all parts of the 
valve motion are located in the same plane. With the 
low pressure cylinders, such an arrangement is impos- 
sible, as the valves are driven by eccentrics which are 
placed on the first axle between the inside crank cheeks. 
The links are mounted on rock shafts, which serve to 
transfer the motion from one plane to the other. Inde- 
pendent reverse shafts are provided for the high and low 
pressure valve gears, which may be operated together or 



UN IVERSAL ADAPTABILITY 



171 



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172 THE WALSCHAERT VALVE GEAR 

separately by means of an ingeniously arranged screw 
reverse mechanism placed in the cab. 

The boiler is of the Belpaire type, built of steel with 
the exception of the inside fire box, which is of copper. 
The grate is placed between the frames and is inclined 
toward the front at a sharp angle, thus giving an excep- 
tionally deep throat. The stay bolts in the water legs 
are of maganese bronze. Each bolt is drilled throughout 
its entire length with a hole ]A, of an inch in diameter. 
These holes are closed up at their inner ends by riveting 
the bolts over after they have been screwed into the 
sheets. The firebox is provided with a brick arch which 
is supported on copper strips, secured to the side sheets 
by copper studs. The grate is of the rocking type. The 
tubes are soft steel, of the "Serve" pattern, with internal 
ribs. 

The boiler shell is built with longitudinal butt joints 
having double covering strips, while the circumferential 
seams are double riveted with lap joints. The throat 
sheet completely encircles the barrel. The cab is built of 
steel plate, and has narrow side windows. Access to the 
running boards may be had by climbing around outside 
of the cab, and for this purpose suitable hand rails are 
provided. An interesting part of the equipment is the 
Haesler Chronotachymetre, which keeps a complete rec- 
ord of the speed throughout the run, and also shows the 
engine men the rates of speed at any instant. The 
motion for this device is derived from a stud which is 
screwed into the rear right hand crank pin, and works 
in a slotted arm on a gear shaft located under the running 
board. 

The tender is carried on six wheels, the two rear pairs 
of which are equalized. The frames are of the plate 
form, placed outside the wheels. 



UNIVERSAL ADAPTABILITY 



173 



The principal dimensions and specifications are as fol- 
lows : 

Type of engine io-wheel DeGlehn Compound 

Service Passenger 

Fuel Bit. Coal 

Tractive force 21,466 lbs. 

Gauge 4 ft. 9 in. 

Cylinders H. P. 14 3-16 in. x 25 3-16 L. P. 23^ 

in. x 25 3-16 in. 

Valve gear, type Walschaert 




FIGURE 86. CROSS SECTION THROUGH BOILER HIGH AND LOW 

PRESSURE CYLINDERS, DE GLEHN FOUR CYLINDER 

COMPOUND— PARIS-ORLEANS RY. 



174 



THE WALSCHAERT VALVE GEAR 



In this connection it will be interesting to note the com- 
ments of Mr. William Forsyth read before the Interna- 
tional Engineering Congress. Speaking with reference 
to the DeGlehn four-cylinder compound locomotive, and 
the Walschaert valve gear, Mr. Forsyth says: 




FIGURE 87. SIDE ELEVATION AND PLAN OF WALSCHAERT 
VALVE GEAR, DE GLEHN FOUR CYLINDER COM- 
POUND — PARIS-ORLEANS RY. 



"The use of the Walschaert valve motion on the Balti- 
more & Ohio Mallet articulated locomotive, and on the 
Pennsylvania Railroad's DeGlehn four-cylinder com- 
pound, which are now on exhibition at Saint Louis, has 
again brought the merits of this gear to the attention of 
American designers. These two locomotives represent 
extreme conditions as to the speeds for which they are 
intended. The one is for slow speed on heavy grades, the 
other for high-speed passenger work. This would indi- 
cate that the Walschaert gear is well adapted to any kind 



UNIVERSAL ADAPTABILITY 175 

of service, freight or passenger. It is fortunate that a 
well-designed gear of this type will soon be seen in oper- 
ation in this country, and its performance on these loco- 
motives will be watched with interest. * * * 

"A valve gear outside of the frames is conveniently 
inspected and repaired, while one inside of the frames is 
certainly in an awkward position for either operation. 
With inside cylinders and crank axles there is little room 
for eccentrics and links, and if all this be removed it al- 
lows ample length for main pin bearings; and it is then 
possible to have an inside bearing for the crank axle. 
The Walschaert gear, as ordinarily designed, is not sym- 
metrical in a vertical plane, and there is a tendency to 
lateral bending and unequal wear when so constructed. 
In the illustrations above referred to Mr. DeGlehn has 
taken special care to avoid these objections, and his de- 
sign shows well-balanced wearing surfaces of ample 
proportions, which should be quite durable. 

"The point to which we wish to call particular attention 
is the great contrast in the weight of the moving parts 
and the size of the bearings when this Walschaert outside 
gear is compared with similar parts of a Stephenson link 
motion driven by eccentrics. A prominent superintendent 
of motive power, who has made a special study of indi- 
cator cards and who has given much attention to valve 
gears, in a recent discussion on 'Modern Tendencies in 
Locomotive Design in America,' made this statement : 
T consider that the increased complication and weight of 
the valve motion is an exceedingly serious matter in giv- 
ing distorted steam distribution, due to the destructive 
effect of the valve motion in causing w r ear and tear/ The 
reports on 'Weights of Detail Parts of Locomotives,' in 
the proceedings of the Master Mechanics' Association, 
1903, page 187, gives the weights of parts of the Stephen- 



176 THE WALSCHAERT VALVE GEAR 

son valve gear for large locomotives, as follows, in 
pounds: Eccentric, 212; eccentric strap, 225; eccentric 
rod, 125; link, 148; rocker arm, 248; transmission bar, 
128; valve rod, 66; valve yoke, 90; valve, 211. These 
figures indicated that the Stephenson valve gear, includ- 
ing the eccentrics and straps, as found on our modern 
locomotives, has become a very ponderous affair. Some 
attention has been given to the valve pattern in the effort 
to make it as light as possible, but the same care has not 
been taken with the moving details connected with it, and 
which easily becomes a disturbing factor at high speeds 
if made too heavy. 

"The principal load w T hich comes on the eccentrics and 
straps, causing them to heat, is not the friction of the 
valve, but it is that due to the inertia of the reciprocating 
parts of the valve gear whose motion is reversed twice 
for every revolution. If we include the rocker arm, the 
weight, as found above, of the moving parts from valve 
to eccentric strap for one cylinder is 1,052 pounds, and at 
high speeds the energy of this moving mass must impose 
a heavy load on the eccentrics. The eccentrics and straps 
are the most difficult details in the locomotive machinery 
to keep properly lubricated, and it requires constant vig- 
ilance to prevent them from heating. When they do heat 
and cut and the straps are taken down, their location in- 
side the frames is the most inconvenient one possible, 
and with the increasing weight of the machinery this part 
of the locomotive repairs has become very laborious and 
expensive. More attention should be given to the re- 
duction of the weight of the moving parts of the Stephen- 
son valve gear, or some other type should be used. The 
Walschaert gear, located outside the frames is easily ac- 
cessible and very convenient for inspection, lubrication 
and repairs. The main driving bearings are two small 



UNIVERSAL ADAPTABILITY 



177 




178 THE WALSCHAERT VALVE GEAR 

pins with bushed bearings, and the contrast with the 
heavy and cumbersome eccentrics and straps which are 
their equivalent in a valve gear system is very striking. 
This gear is simple and light throughout, and it has much 
to recommend it which would overcome the objectionable 
features of the shifting link motion driven by eccentrics." 

Another example of the adaptability of this valve gear 
to any and all kinds of railway service is seen in the Mal- 
let compound locomotive which has within the past four 
years been successfully introduced into the United States. 
Figures 88 and 89 will serve to illustrate in general the 
design of this type of locomotive. 

Although a radical departure from the usual design in 
use in this country, the performance of the locomotive has 
been entirely satisfactory from the standpoints of oper- 
ation and maintenance. The success of this type led to its 
adoption by the Northern Pacific Railway, first for helper 
service and later for regular road work. The latest de- 
velopment in this type is the locomotive lately completed 
at the Schenectady Works of the American Locomotive 
Company for the Erie Railroad, which is the heaviest and 
most powerful locomotive in the world. 

The enormous size and capacity of this locomotive is 
shown by the total weight of 410,000 pounds, all of w T hich 
is on the drivers and the available tractive force of 94,800 
pounds. The locomotive was designed for pusher serv- 
ice between Susquehanna and Gulf Summit where the 
grade is T.3 per cent. If the tractive force is maintained 
the locomotive should handle over 3,000 tons in a train 
of 60 cars up the grade in fair weather, which demon- 
strates the capacity of the locomotive and its adaptability 
to helper service on heavy grades. 

The engines are compounded on the Mellin System, the 
intercepting valve being located in the upper part of the 



UNIVERSAL ADAPTABILITY 179 

left cylinder casing. Exhaust steam from the right high 
pressure cylinder passes through a cored passage to the 
back of the cylinder casing, from whence it passes 
through a U-shaped pipe connecting to a passage in the 
left cylinder casting leading up into the intercepting valve 
chamber, into which the exhaust steam from the left high 
pressure cylinder also passes. 

The emergency exhaust valve is located in the side of 
the left cylinder casting, and has a four and one-half-inch 
jointed pipe connection within an opening in the back of 
the nozzle in the smoke box. 

Steam from the high pressure cylinders passes into a 
nine-inch receiver pipe extending forward from the cen- 
ter of the cylinder saddle, to which it is connected by a 
ball joint. 

In order to facilitate putting in place or removing, this 
pipe is made up of three sections, and is connected at the 
front end by means of a slip joint to cover variations in 
length, due to curving to a Y pipe through which steam 
reaches each of the low pressure steam chests. 

The receiver pipe is laid out for 16 degree curves. 
Steam from the low pressure cylinders, w T hich are located 
considerably ahead of the front end of the boiler, ex- 
hausts back through a flexible pipe connection to the ex- 
haust pipe in the smoke box. 

The high pressure cylinders are equipped with piston 
valves, and the low pressure cylinders with the Richard- 
son slide valves, described in another part of this book. 

The valve gear is of the Walschaert type, and by an in- 
genious arrangement of the reversing gear, the weights 
of the valve motions of the front and rear engines coun- 
ter-balance each other. 



180 



THE WALSCHAERT VALVE GEAR 



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UNIVERSAL ADAPTABILITY 181 

The valve motion is reversed by means of a pneumatic 
operating device. 

Fig. 90 shows a consolidation freight locomotive of the 
Lake Shore and Michigan Southern Railway equipped 
with the Walschaert gear and the following interesting 
comparison of the weights of this gear and the Stephen- 
son link motion is made by the American Engineer and 
Railroad Journal, using the locomotive shown in Fig. 90 
as an example : 

"In the matter of weight of parts, the details, in pairs, 
of the Walschaert gear of this engine (Lake Shore & 
Michigan Southern 2-8-0 type No. 912) are as follows: 
Cross-head arms, 60 pounds ; vibrating rods, 220 pounds ; 
eccentric rods, 220 pounds ; links, 260 pounds ; transmis- 
sion bars, 140 pounds ; valve rods, 70 pounds ; eccentric 
cranks, 100 pounds ; vibrating links, 70 pounds ; valve 
stems, y2 pounds ; and transmission bar hangers, J2 
pounds. This means a total weight of 1,252 pounds for 
the entire valve gear of the Lake Shore engine, not in- 
cluding the valves. The weight of the corresponding 
valve gear parts of a recently constructed 20x28-inch, 
4-6-0 engine, with Stephenson link motion, is 2,734 
pounds. Such a weight, which must be moved and re- 
versed for every revolution, imposes severe duty upon the 
eccentrics, and it is not surprising that they heat." 

Figs. 91 and 92 illustrate examples of recent construc- 
tion of locomotives equipped with the Walschaert valve 
gear by the Baldwin Locomotive Co. 

Referring to Fig. 91 the general dimensions are as fol- 
lows : 

Gauge 4 feet 8 V2 inches 

Cylinders 28x32 inches 

Valve Balanced 

Boiler — type ,, ? Wagon top 



182 



THE WALSCHAERT VALVE GEAR 




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184 THE WALSCHAERT VALVE GEAR 

Material Steel 

Diameter .. . 78^4 inches 

Thickness of Sheets }i and 15/16 inches 

Working Pressure 160 lbs. 

Fuel > Soft Coal 

Staying Radial 

Firebox — Material Steel 

Length 108 inches * 

Width 78 inches 

Depth front, 8oj4 inches ; back, ySyi inches 

Thickness of Sheets, .sides, Y% inches; back, }i inches; 

crown, }$ inches; tube, 9/16 inches 

Water Space front, 4V2 inches ; 

sides, 5 inches ; back, 4 inches - 

Tubes — Material Steel 

Wire Gauge No. 1 1 

Number 391 

Diameter 2*4 inches - 

Length 20 feet 

Heating Surface — Firebox 210.0 sq. ft. 

Tubes 4586.0 sq. ft. 

Total 4796.0 sq. ft. 

Grate Area 58.5 sq. ft. 

Driving Wheels — Diam. Outside 57 inches 

Diameter of Center 50 inches 

Journals main, 11x12 inches 

others, 10x12 inches 

Engine Truck Wheels — 

Diameter, front .29*4 inches 

Journals 6^x10^ inches 

Diameter, back 40 inches 

Journals 7J/2X12 inches 



UNIVERSAL ADAPTABILITY 185 

Wheel Base — Driving 19 feet 9 inches 

Rigid 19 feet 9 inches 

Total engine 35 feet 11 inches 

Total Engine and Tender 67 feet 4 J/2 inches 

Weight — On Driving Wheels 2 33>35° lt> s - 

On Truck, front 24,800 lbs. 

On Truck, back 22,300 lbs. 

Total Engine 280,450 lbs. 

Total Engine and Tender about 430,000 lbs. 

Tender — Number of Wheels 8 

Diameter of Wheels 33 inches 

Journals 5>4xio inches 

Tank — Capacity Water, 8500 gals. 

Coal, 14 tons 
Service — Freight. 

Engine equipped with Baldwin Super-heater. Super- 
heating surface, 762 square feet. 



THE WALSCHAERT VALVE GEAR. 

Freight Locomotive — Consolidation Type, with Wals- 

chaert Valve Gear. Built for Lake Shore & 

Michigan Southern Railway. 

(See Fig. 90.) 

Gauge of Track, 4 feet 8*4 inches. 

Loaded Weights 

On leading track 25,000 pounds 

On driving wheels 198,000 pounds 

Total engine 223,000 pounds 

Tender 141,500 pounds 

Wheel Base 

Driving 17 feet 

Total of engine 25 feet 1 1 inches 

Total of engine and tender 60 feet 6 l / 2 inches 

Cylinders 

Diameter 23 inches 

Stroke of piston 32 inches 

Valves, piston type 

Wheels 

Diameter of engine truck wheels 33 inches 

Diameter of driving w 7 heels, outside 63 inches 

Diameter of tender wheels 33 inches 

186 



the walschaert valve gear 187 

Journals — Diameter and Length 

Engine truck 6*4x10 inches 

Driving 10 and 9^x12 inches 

Tender 5 V2X10 inches 

Type, 280-223 

Boiler 

Type Straight Top 

Outside diameter at front end 81^ inches 

Length of fire-box, inside 106 inches 

Width of fire-box, inside 76 inches 

Number of tubes 460 

Diameter of tubes 2 inches 

Length of tubes 15 feet 6 inches 

Working pressure per square inch 200 pounds 

Heating surface in tubes 3,709.42 sq. feet 

Heating surface in fire-box 182.5 sq. feet 

Total heating surface 3,921.92 sq. feet 

Grate area 54.9 sq. feet 

Tender Capacity 

Water 7>5°° gallons 

Fuel 12 tons 

Clearance Limitations 

Height of stack above rail 14 feet g}i inches 

Width 10 feet 2]/ 2 inches 

Length over all 70 feet \]/\ inches 

Maximum Tractive Power, 45,685 pounds. 
American Locomotive Company. 



188 THE WALSCHAERT VALVE GEAR 

Switching Locomotive, zvith Walschaert Valve Gear — 

Built for the Lake Shore & Michigan 

Southern Railway. 

(Heaviest Switching Locomotive Ever Built.) 

(See Fig. 93.) 
Gauge of Track, 4 feet 8V 2 inches 

Loaded Weights 

On driving wheels 270,000 pounds 

Total engine 270,000 pounds 

Tender 149,000 pounds 

Wheel Base 

Driving 19 feet 

Total of engine 19 feet 

Total of engine and tender 54 feet 5^ inches 

Cylinders 

Diameter 24 inches 

Stroke of piston 28 inches 

Valves, piston type 

Wheels 

Diameter of driving wheels, outside.. 52 inches 

Diameter of tender wheels 33 inches 

Journals — Diameter and Length 

Driving 10^x9^x12 inches 

Tender 5^x10 inches 

Type, 0100-270 



THE WALSCHAERT VALVE GEAR 



189 




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190 the walschaert valve gear 

Boiler 

Type Extended Wagon Top 

Outside diameter at front end 80 1/16 inches 

Length of fire-box, inside 108^ inches 

Width of fire-box, inside 73 l A inches 

Number of tubes 447 

Diameter of tubes 2 inches 

Length of tubes . 19 feet 

Working pressure per square inch 210 pounds 

Heating surface in tubes 4,422.4 sq. feet 

Heating surface in fire-box 203 sq. feet 

Total heating surface 4,625.4 sq. feet 

Grate area 55 sq. feet 

Tender Capacity 

Water 8,000 gallons 

Fuel 12 tons 



Clearance Limitations 

Height of stack above rail 14 feet 10^4 inches 

Width 10 feet 2 inches 

Length over all 70 feet 4 inches 

Maximum Tractive Power, 55,362 pounds. 
American Locomotive Co. 



THE WALSCHAERT VALVE GEAR 191 

Passenger Locomotive — Prairie Type, with Walschaert 
Valve Gear — Built for Pennsylvania Railroad 

(American Locomotive Co.) 
(See Fig. 94.) 
Gauge of Track, 4 feet 9 inches. 

Loaded Weights 

On leading truck 27,000 pounds 

On driving wheels 166,800 pounds 

On trailing truck 40,700 pounds 

Total engine 234,500 pounds 

Tender 139,300 pounds 

Wheel Base 

Driving 14 feet 

Total of engine 34 feet 3 inches 

Total of engine and tender 64 feet 6^4 inches 

Cylinders 

Diameter 21^4 inches 

Stroke of piston 28 inches 

Valves, piston type 

Wheels 

Diameter of engine truck wheels A^/2 inches 

Diameter of driving wheels, outside 80 inches 

Diameter of trailing wheels 50 inches 

Diameter of tender wheels 36 inches 



192 



THE WALSCHAERT VALVE GEAR 






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Journals — Diameter and Length 

Engine truck 6^x12 inches 

Driving 10x12 inches 

Trailing 8x14 inches 

Tender 5^x10 inches 

Type 262-235 
Boiler 

Type Straight Top 

Outside diameter at front end 74^ inches 

Length of fire-box, inside ioS 1 /^ inches 

Width of fire-box, inside 73*4 inches 

Number of tubes 322 

Diameter of tubes 2j4 inches 

Length of tubes 19 feet 6 inches 

Working pressure per square inch 200 pounds 

Heating surface in tubes 3,678.9 square feet 

Heating surface in fire-box 202.7 square feet 

Total heating surface . . .3,881.6 square feet 

Grate area 55 square feet 

Tender Capacity 

Water 7,000 gallons 

Fuel 10 tons 



Clearance Limitations 

Height of stack above rail 14 feet 10^/s inches 

Width 10 feet }i inches 

Length over all 73 feet 10 /s inches 

Maximum Tractive Power, 27,520 pounds. 



GENERAL DIMENSIONS. 

(See Fig. 95.) 

Gauge 3 feet 6 inches 

Cylinders 16-inch diam. x 22-inch stroke 

Valve Balanced Piston 

Boiler — Type , Straight 

Material Steel 

Diameter 51 inches 

Thickness of Sheets y 2 inch 

Working Pressure 200 lbs. 

Fuel Lignite 

Staying Radial 

Firebox — Material Copper 

Length 82 inches 

Width 30 inches 

Depth front, 5634 inches ; back, 47^ inches 

Thickness of Sheets sides, V 2 inch; back, ]/ 2 inch; 

crown, ^s inch ; tubes, ^4 an d V* inch 

Water Space front, 3^ inches ; sides, 2^ inches ; 

back, 2j4 inches 

Tu'bes — Material Copper 

Wire Gauge No. 1 1 and No. 12 

Number, 197 Diameter, 134 inches 

Length 13 feet 10 inches 

Heating Surface — Firebox 81.8 sq. ft. 

Tubes 1238.5 sq. ft. 

Total !320.3 sq. ft. 

Driving Wheels — Diam. Outside 49 inches 

Diameter of Center 44 inches 

Journals 6^x7 inches 

194 



GENERAL DIMENSIONS 



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196 THE WALSCHAERT VALVE GEAR 

Engine Truck Wheels — 

Diameter 26 inches 

Journals 4/4 x 7^ inches 

Wheel Base — Driving 10 feet 

Rigid ........ . . IO feet 

Total Engine 21 feet 5^2 inches 

Total Engine and Tender 47 feet 

Weight — On Driving Wheels 61,570 lbs. 

On Truck, front 23,180 lbs. 

Total Engine 84,750 lbs. 

Total Engine and Tender 145,000 lbs. 

Tank — Capacity .Water, 3,000 gals. 

Coal, 6 tons 

Tender — Number of Wheels 8 

Diameter of Wheels 33 inches 

Journals 4/4x8 inches 

Figs. 96 and 97 are introduced for the purpose of illus- 
trating the remarkable adaptability of the Walschaert 
valve gear to any and all conditions and requirements of 
locomotive service, no matter how rigid may be the de- 
mands. 



VARIOUS TYPES 



197 




FIGURE 96. RACK LOCOMOTIVE FOR THE MAXITOU AND PIKE 
PEAK RAILWAY, 1890. 
Baldwin Locomotive Works. 



198 THE WALSCHAERT VALVE GEAR 



FIGURE 97. RACK LOCOMOTIVE FOR THE LEOPOLDINA 

RAILWAY, 1897. 

Baldwin Locomotive Works. 



VARIOUS TYPES 



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THE WALSCHAERT VALVE GEAR 




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THE WALSCHAERT VALVE GEAR 




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WALSCHAERT VALVE GEAR. 

INDEX. 

A. 

Adjustment of Walschaert valve gear 3 I_ 36 

Admission, outside and inside 20, 24, 39, 40, 41 

Advantages of Walschaert valve gear over Stephen- 
son link 1 50 

Alfree valve 1 13-124 

Allen valve 58-61 

Allen-Richardson balanced slide valve 57 - 6o 

American balanced valve 94-104 

American Balanced Valve Company's Piston valve. 41-45 

Angular advance 130-131 

increase of 134-135 

Angularity of connecting rod 22 

B. 

Back pressure 81 

Balances, American Balance Valve Co/s 103 

Balance plate 46, 50, 53, 55 56 

Balance plate, semi-circular 78, 107 

Balance strips 107 

Balanced valves 45 _ 77 

American 94-104 

Barnes Balanced Valve 106 

Briggs Balanced Valve 109 

Back cylinder head broken 156-157 

Breakdowns 1 5o-iS7 

i 



11 INDEX 

c. 

Combination lever 24-38, 154-155 

fulcrum of 143 

Combination of two motions 31 

Connecting rod, angularity of 22 

Crank, position of 129 

Compression 75, 76, 113, 116, 123, 129 

Compression controlling valve 122-123 

Cut-off auxiliary 66-67 

Cut-off valve, Goodspeed's 61-67 

Cylinder relief 103-104 

Consolidation engine, dimensions of 186 

D. 

D slide valve 37, 38, 53 

Details of construction Walschaert valve gear. ... 18-23 

Details of adjustment Walschaert valve gear 3 I- 36 

Diagrams, Indicator 123, 124 

Valve 125-139 

DeGlehn Compound, dimensions of 168-173 

arrangement of cylinders 168-170 

E. 

Eccentric, position of 23 

Eccentric, reversal of 31 

Eccentric, throw of 33 

Eccentric, difficult inspection of 12, 14, 18 

Eccentric, Walschaert valve gear 10, 14, 23 

Eccentric rod, variations in length of 2 3~3 l 

Engine, Reversal of 31 

Equal cut-offs 10 

Eccentric crank or rod broken 150-152 

Eccentric, what causes heating of 176 



INDEX 111 

F. 

Farrer's slide valve , 20 

Formula for determining friction of valve 112 

Formulae of Balance, American balance valve. . 104-105 
Fulcrum of link 20 

G. 

Goodspeed cut-off valve 61-67 

Gould balance valves 78-83-88 

H. 

Haley's slide valve 67-72 

Heat losses, reduction of 113-115 

I. 

Increased turning effect 116 

Independent valve face 67-68 

Inside clearance 69 

Inside lap 69 

Joint ring 109-1 10 

L. 

Lap, inside 69 

Lap, outside 20, 33, 128, 132 

Lap, increase of 132, 135 

Lead, constant of Walschaert gear 14, 20, 33, 142 

Link, methods of suspension 10, 11 

Link, radius of 12 

Link, location of 12-25 

Link block 11, 20, 25 

Link fulcrum, position of 22 

Lifter, point of suspension 20, 22 



IV INDEX 

Lead, what it is 141 

Lead, reason for variation, with Stephenson link.141-142 
Lead, why constant with Walschaert gear 142-143 

M. 

Mallet compound, dimensions of 16-17, 174-178 

Margo valve in 

Metzger's slide valve 7 1 -? 2 

McDonald valve 109 

Mellin system 178-179 

O. 

Operation of Walschaert valve gear 144-149 

Over travel of valve 53 _ 55 

P. 

Packing rings 49, 87, 94, 109 

Packing strips 56-57 

Piston valve 37, 45, 89, 91, 94 

Piston valve, advantages of 45"9° 

Pressure plate 49-5 1 

Passenger engine, general dimensions of 191 

Piston broken I 55~ I 56 

q. 

Quick action valve 78-83 

Questions 158-166 

R. 

Radius rod, length of 11, 20, 143 

Recent constructions, dimensions of 181-185 

Release 129-130 

Richardson balanced valve 55-57 

Rings, packing 49 



INDEX V 

Rings, balancing 50-5 1 

Rings, centering 50 

Roller valve yy 

S. 

Saving in weight, Walschaert over Stephenson link. . 

19-20-21 

Semi-circular valve 86 

Service results 167 

Side rod, breakage of 150 

Sliding block 1 1-20 

Slide valve, D 37-38-53 

Slide valve, Haley's 67-72 

Slide valve, Metzger's 7^~7^ 

Slide valve, Farrers 75 _ 76 

Steam chest 51 

Switching engine L. S. & M. S., dimensions of 188 

T. 

Travel of valve 24 

Travel of valve, effect of decreasing 131-132 

U. 
U shaped packing strips . 108 

V. 

Valve action 125-127 

Valve, types of for locomotive 37, no 

Valve, how to block 151 

Valve, travel 24 

Valve, vacuum relief 88-89 

Valve gear, Walschaert, general description 10-17 

Valve gear, comparison of Walschaert and Stephen- 
son 10 



VI INDEX 

Valve gear, ease of handling Walschaert 16 

Valve gear, necessity of inspection and lubrication.. 18 

Valve stem, broken 153-154 

Valve cover 80, 86, 87 

Valve motion, Sharps , . . 8 

Vauclain compound locomotive 91-94 

W. 

Walschaert, sketch of career 2-9 

Walschaert, list of inventions 2 

Walschaert valve gear, original design of 4-6 

Walschaert valve gear, modern design 6-8 

Walschaert valve gear, details of construction .... 18-23 

Walschaert valve gear, use of in Europe 18 

Walschaert valve gear, reasons for applying 18-19 

Walschaert valve gear, saving in weight 19-20 

Walschaert valve gear, detailed weight of 21 

Walschaert valve gear, method of laying out 2 4~30 

Walschaert valve gear, details of adjustment 3 I ~36 

Watkey's valve 73 _ 74 

Wilson balanced valve 46-50 

Wire drawing of steam 58 

Weight of Stephenson gear 176 

Z. 
Zeuner diagram 136-138 



REVISED AND ENLARGED 1908 EDITION 



MODERN LOCOMOTIVE 
ENGINEERING 



20th Century 
Edition 



By C. F. SWINGLE, M. E* 




THE most modern and practical work published, treating upon the 
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The aim of the author in compiling this work was to furnish to loco- 
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Breakdown, and what to do in cases of emergency, are given a con- 
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The book contains over 800 pages and is beautifully illustrated with 
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Ghe 20th Century Hand Book 

FOR 

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A COMPENDIUM 
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Engines, Boilers and 
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tion tests on boilers. 
The adjustment of the 
slide valve, corliss 
valves, etc., fully de- 
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together with the ap- 
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analysis. The subject 
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By C. F. SWINGLE, M.E. 

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Over three hundred questions by practical Locomotive 

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problems met with. Answered by W. G. Wallace 

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Railroading 



OR 



Electricity as Applied to Railroad 
= Transportation = 

By SIDNEY AYLMER-SMALL, M. A. I. E. E. 




T , 



^HE coming of the Electric 
Locomotive is no longer 
a matter of speculative theory. 
It is here. Now it is merely a 
question of gradual develop- 
ment and improvement, until 
in time it will displace the 
steam locomotive. 
Ct, In this book Mr. Sidney Ayl- 
mer-Small leads the reader up 
through the elementary stages 
of electricity, and onward until 
he has made him so familiar 
with the subject that he readily 
comprehends how it is applied 
to railway operation at the present time. 

12mo. Full Leather Limp, 910 pages, 540 
Illustrations and 8 Folding Plates. Price, $3.50 



SENT POSTPAID TO ANY ADDRESS IN 
THE WORLD UPON RECEIPT OF PRICE 



FREDERICK J. DRAKE & CO. 

PUBLISHERS 

Chicago, 111. 



STEAM BOILERS, THEIR 
CONSTRUCTION, CARE 
AND OPERATION, ratSS 



By C. F. SWINGLE, M. L. 



A complete modern treatise, fully describing, with illus- 
trations, the steam boiler of various types. Construction and 

rules for ascertaining the 
strength for rinding safe 
working pressure. Boiler? 
settings and appurtenances 
grate surface insulation, 
cleaning tubes, safety 
valve calculations, feed 
pumps, combustion, evap- 
oration tests with rules, 
strength of boilers, and 
mechanical stokers. 200 
pages, fully illustrated. 

The latest and most 
complete treatise on boilers 
published. 1 6 m o . Full 
leather limp binding. 




PRICE NET 

$1.50 



Sent Postpaid to any Address in the World upon Receipt of Price 

FREDERICK J. DRAKE & CO. 

PUBLISHERS 

CHICAGO, ILL. 



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